August 2 1, 1879] 



NATURE 



385 



tion by I'rof. Haeclel, who believes that he is able to confirm 

 ill all points the conclusions of Huxley, and arrives at the 

 conviction that the bottom of the open ocean, at depths below 

 5,000 feet, is covered with an enormous mass of living proto- 

 plasm, which lingers there in the simplest and most primitive 

 condition, having as yet acquired no definite form. He suggests 

 that it may have originated by spontaneous generation, but leaves 

 this que.'tion for future investigations to decide. 



The reality of Bathybius, however, has not been universally 

 accepted. In the more recent investigations of the Challenger 

 the explorers have failed in their attempts to bring further 

 evidence of the [existence of masses of amorphous protoplasm 

 spreading over the bed of the ocean. They have met with no 

 trace of Bathybius in any of the regions explored by them, and 

 they believe that they are justified in the conclusion that the 

 matter found in the dredgings of the Porcupine and preserved in 

 spirits for further examination, was only an inorganic precipitate 

 due to the action of the alcohol. 



It is not easy to believe, however, that the very elaborate 

 investigations of Huxley and Haeckel can be thus disposed of. 

 These, moreover, have received strong confirmation from the 

 still more recent observations of the Arctic voyager, Bessels, who 

 was one of the explorers of the ill-fated Polaris, and who states 

 that he dredged from the Greenland seas masses of living un- 

 diflferentiated protoplasm. Bessels assigns to these the name of 

 Protobathybius, but they are apparently indistinguish.able from 

 the Bathybius of the Porcupine. Further arguments against the 

 reality of Bathybius will therefore be needed before a doctrine 

 founded on observations so carefully conducted shall be relegated 

 to the region of confuted hypotheses. 



Assuming then, that Bathybius, however much its supposed 

 wide distribution may have been limited by more recent re- 

 searche-, has a real existence, it presents us with a condition of 

 living matter the most rudimental it is possible to conceive. No 

 law of morphology has as yet exerted itself in this formless 

 slime. Even the simplest individualisation is absent. We have 

 a living mass, but we know not where to draw its boundary lines ; 

 it is living matter, but we can scarcely call it a living being. 



We are not, however, confined to Bathybius for examples of 

 protoplasm in a condition of extreme simplicity. Haeckel has 

 found, inhabiting the fresh waters in the neighbourhood of Jena, 

 minute lumps of protoplasm, which when placed under the 

 microscope were seen to have no constant shape, their outline 

 being in a state of perpetual change, caused by the protnision 

 from various parts of their surface of broad lobes and thick 

 finger-like projections, which, after remaining visible for a time, 

 would be withdrawn, to make their appearance again on some 

 other part of the surface. 



These changeable protrusions of its substance, without fixed 

 position or definite form, are eminently characteristic of proto- 

 plasm in some of its simplest conditions. They have been 

 termed " P.-cudopodia," and will frequently come before you in 

 what I liave yet to say. 



To the little protoplasmic lumps thus constituted, Haeckel 

 has given the name of Protamceia pritni/iva. They may be 

 compared to minute detached pieces of Bathybius. He has 

 seen them multiplying themselves by spontaneous division into 

 two piece--, which, on becoming independent, increase in size 

 and acquire all the characters of the parent. 



Several other beings as simple as Protamaba have been de- 

 scribed by various observers, and especially by Haeckel, who 

 brings the whole together into a group to which he gives the 

 name of Monera, suggested by the extreme simplicity of the 

 beings included in it. 



But we must now pass to a stage a little higher in the develop- 

 ment of protoplasmic beings. Widely distributed in the fresh 

 and salt waters of Britain, and probably of almost all parts of 

 the world, are small particles of protoplasm closely resembling 

 the Protamaba just described. Like it, they have no definite 

 shape, and are perpetually changing their form, throwing out 

 and drawing in thick lobes and finger-like pseudopodia, in 

 which their body seems to flow away over the field of the micro- 

 scope. They are no longer, however, the homogeneous particle 

 of protoplasm which forms the body of Prolamaba. Towards 

 the centre a small globular mass of firmer protoplasm has 

 become differentiated off from the remainder, and forms what 

 is known as a nucleus, while the protoplasm forming the extreme 

 outer boundary differs slightly from the rest, being more trans- 

 parent, destitute of granules, and apparently somewhat firmer 

 han the interior. We may also notice that at one spot a clear 



spherical space has made its appearance, but that while we 

 watch it has suddenly contracted and vanished, and after a few 

 seconds has begun to dilate so as again to come into view, once 

 more to disappear, then again to return, and all this in regular 

 rhythmical sequence. This little rhythmically pulsating cavity 

 is called the "contractile vacuole." It is of very frequent oc- 

 cun-ence among those beings which lie low down in the scale of 

 life. 



We have now before us a being which has arrested the atten- 

 tion of naturalists almost from the commencement of microscop- 

 ical observation. It is the famous Amaba, for which ponds and 

 pools and gutters on the house roof have for the last 200 years 

 iieen ransacked by the microscopist, who has many a time stood 

 in amazement at the undefinable form and Protean changes of 

 this particle of living matter. It is only the science of our own 

 days, however, which has revealed its biological importance, and 

 shown that in this little soft nucleated particle wc have a body 

 whose significance for the morphology and physiology of living 

 beings cannot be over estimated, for in Amaba we have the essen- 

 tial characters of a CELL, the morphological unit of organisation, 

 the physiological source of specialised function. 



Tlie term " cell " has been so long in use that it cannot now be 

 displaced from our terminology ; and yet it tends to convey an 

 incorrect notion, suggesting, as it does, the idea of a hoUovr 

 body or vesicle, this having been the form under which it was first 

 studied. The cell, however, is essentially a definite mass of 

 protoplasm having a nucleus imbedded in it. It may, or may 

 not, assume the form of a vesicle ; it may, or may not, be pro- 

 tected by an enveloping membrane ; it may, or may not, contain 

 a contractile vacuole ; and the nucleus may, or may not, contain 

 within it one or more minute secondary nuclei or "nucleoli." ""■ 



Haeckel has done good service to biology in insisting on the 

 necessity of distinguishing such non-nucleated forms as are pre- 

 sented by Prolamccba and the other Monera from the nucleated 

 forms as seen in Ainceba. To the latter he would restrict the 

 word cell, while he would assign that of "cytode " to the former.' 



I In every typical cell three parts may be distinguished. There is first the 

 more or less liquid granular protoplasm ; secondly the nucleus; and thirdly 

 an external more firm zone of protoplasm, known as the ' cortical layer '— 

 the Hautschicht of the German histoiogists. All these parts may bereg.arded 

 as portions differentiated out of the original simple protoplasm. Cells do 

 net, however, always remain on a stage of such simplicity as that presented 

 hy A}ti(rba. The nucleus is always at its origin quite homogeneous, but as 

 it increases in size it usually manifests a differentiation resuhing in a consti- 

 tution which recent research has shown to be more complex than had been 

 previously supposed : for we often find it to present an external firmer layer, 

 or nuclear membrane, including within it the scfter nuclear protoplasm, 

 in which again a network of filaments has been in many instances described. 



The structure of the nucleus has been quite recently studied by Flemming 

 (Arch./, mikr. Anal., E.ind xvi. Heft 2, 1S7S), who has given particular 

 attention to this intranuclear network. He maintains that m its completed 

 state the nucleus consists of a parietal firm layer, which incloses, besides 

 specially differentiated nucleoli, a framework (Geriist) of filaments with a 

 more fluid inters-ening substance. He further insists on the fact that, with 

 the differentiation of a nucleus, there is introduced a chemical difl^erence 

 between its substance and that of the surrounding cell substance, as shown 

 not only by a different behaviour of the nucleus towards re-agents, but by an 

 actually determined difference of chemical composition. 



K\t\n (Qunr/c'rly Joiirn. Micr. Sci. vol. xviii. p. 3r5)h.i5 shown that in 

 the cells of the stomach of Triton cristatus there is a delicate intranuclear 

 network of filaments in all respects resembling that described by I'lemming ; 

 and he further maintains that the network of the nucleus is here continuous, 

 through minute apertures near the poles of the nuclear membrane, with a 

 similar network in the surrounding cell-substance. In this cell-substance he 

 distinguishes two parts— the homogeneous ground substance and the intra- 

 cellular network of filaments. 



Flemming, however, will not admit this crnnection between intra-nuclear 

 and intra-celluUar fil.aments, and Schleicher, .xs the result of his very recent 

 researches on the division of cartilage-cells (" Die Kncrpelzelltheilung," Arch, 

 f. mikr. Amtt.. Band xvi. Heft 2, 1878), concludes that in these there is no 

 true intra cellular network, the nucleus being here composed of a multitude 

 of separate rodlets, filaments, and granules surrounded by the nucle.Tr 

 membrane. 



The ininule granules which are generally seen in the soft pr> toplasm ot 

 the cell do n t seem to be essential constituents. They are probably nutn- 

 tive matter introduced from without, and in process of assimilation and 

 conversicn into proper protoplasm. Hanstein has distinguished by the term 

 Metaplasm these granules from the proper homogeneous pr , toplasm in which . 

 they are suspended. The external cortical layer is quite de.-titute of them : 

 on this devolves the property of protecting the contents from the unfavour- 

 able action of outer influences, and to it alone in plants is allocated the 

 property of secreting the cellulose boundary wall. 



Several recent observers, but mote especially Str.asburper (" Studien iiber 

 das Protoplasma," Jenaische Zeitschr., 1876), have described in the cortical 

 layer of various cells a radial striation, as if formed by excessively delicate 

 rodlets (St.'ibchen), placed vertically to the surface and in close proximity to 

 one another. He has seen a relation between these and the cilia on tne 

 swarm spores 06 Vaucheria, where each cilium seems to be suppc rled by a 

 rodlet. That this condition of the cortical layer, however, has not a general 

 feature ot cell protoplasm, is certain ; it is but a special case of structural 

 difl'crentiation. Indeed, the complex structure which has been detected m 

 the nucleus and in the surrounding cell-protoplasm can scarcely be other- 



