114 



KNOWLEDGE 



[May 1. 1899. 



mouth, a depth of about seven thousand eight hundred 

 feet, or apparently many times that of the deepest known 

 of Norwegian fiords. 



With the advent of period (b) and submergence of the 

 edge of the continental platform, conditions changed to 

 some extent. As the shore line retreated up the gentle 

 slope of the continental platform, every part of the sub- 

 merged gorge became, in turn, silt trap for the travelling 

 coast sediments, and under conditions of slow subsidence 

 the channel would have been gradually filled up and 

 obliterated from the mouth upwards if not from both ends. 

 As this did not happen it must be again inferred that either 

 there was no shore deposit going on at the time, or 

 the rapidity of submergence was such that the amount of 

 travelling coast sediment trapped by the deep trough 

 during the process was insignificant. 



In each case it seems more natural to adopt the second 

 alternative mentioned — that is, great rapidity of sub- 

 mergence — especially as to adopt the other involves a series 

 of implications which have the character of gratuitous 

 assumptions. The question then imposes itself : " What 

 rate of subsidence — and if of subsidence why not of 

 upheaval — constitutes a catastrophe '? " 



THE MYCETOZOA, AND SOME QUESTIONS 

 WHICH THEY SUGGEST.-III. 



By the Eight Hon. Sir Edward Fry, d.c.l., ll.d., f.r.s., 

 and AcJNES Fry. 



SPECIES.^That true species exist in the myxies is 

 doubted by no one who has studied them, and 

 the constancy of many forms from distant places 

 strongly supports this view. But it may be per- 

 mitted to doubt whether the range of variation 

 possible to one and the same species is yet sufficiently 

 known to enable us to rely with security upon the whole of 

 the present classification. In the progeny of a common 

 parent when under cultivation, great diversities have been 

 observed in the character of the calcareous walls of the 

 sporangium, in the thickness of the capillitium, and even 

 in its presence or absence, in the colour of the sporangium 

 walls, the capillitium, and even of the plasmodium. Until, 

 therefore, more species have been subjected to observations 

 under culture, or more life-histories have been exactly 

 traced, we must be prepared to regard the specific distinc- 

 tions as open to revision. Mr. Massie considers that he 

 has found cases of hybridism in myxies ; but this, perhaps, 

 requires confirmation. 



Whatever be the limits of variation within a species, the 

 great fact of specific distinction seems to admit of no 

 doubt, and one of the most interesting faculties of these 

 pieces of naked protoplasm is the power of Icnowing 

 other pieces of protoplasm of their own species from the 

 apparently similar protoplasm of other species. According 

 to the concurrent testimony of three of the chief observers 

 of these organisms, Cienkowski, De Bary, and Lister, 

 " imion never takes place between plasmodia of diflerent 

 species." "Branches of different plasmodia," says 

 Cienkowski, " crawl near one another, and mutually 

 embrace one another, without showing the least trace of 

 any fusion." 



The merging of two protoplasms has been seen under the 

 microscope. " There appeared to be no mutual attraction 

 until the two plasmodia were only separated by a distance of 

 40 /i. When a lobe from one was pushed out towards 

 its companion, the intervening swarm cells were thrust 

 aside, and they came into contact ; the hyaloplasm 

 (ectoplasm) of each blended at a single point, and then a 



stream of granular matter was seen to pass, then with a 

 return flow of the streaming in the layer of the two, 

 the channel was widened, and a gush of its contents 

 poured into the smaller one, when union was complete and 

 the system of circulation became common to both.' 



It may be permissible to adduce another instance of 

 organisms of a very simple character to illustrate at once 

 the attractive force of members of one species on their 

 fellows, and of the capacity for selection which makes 

 them reject the members of other, though very similar 

 species. The case we are about to mention relates to two 

 species of the genus i'utleria, algip of a low type. 



To the receptive ova of Cutleria adspersa, Falkenburg 

 added actively mobile spermatozoids of the nearly allied 

 species Cutleria multirida ; so like the other species adspersa 

 that they can only be distinguished by small external 

 difl'erences. " In this case the spermatozoids, as seen by 

 ; the microscope, wandered aimlessly about, and finally died 

 ! without having fertilized the ova of the allied species of 

 algie. ... A very different result was obtained as soon 

 as a single fertilizable ovum of the same species was intro- 

 duced into the vessel containing the spermatozoids. After 

 a few moments, all the spermatozoids from all sides 

 gathered around this ovum, even when the latter was 

 several centimetres distant from the place at which the 

 latter were chiefly collected." 



These instances impress the mind with the fundamental 

 character of the fact of species ; whether it has arisen from 

 variation and selection or not, it is a fact that goes down 

 to the very foundations and rudiments of organic life, and 

 even there influences the life and habits of the organism. 

 As we see it in the myxies, it precedes the origination of 

 the sexual distinction, it precedes any ditt'erentiation of 

 parts or organs, it precedes the development of the cellular 

 tissue. It may, perhaps, be said to precede the division 

 into the animal and vegetable kingdoms. The distinction 

 can exist in small naked bits of protoplasm, and each of 

 these, indistinguishable in structure as the protoplasts of 

 some of the species are to any organs or instruments which 

 we possess, has the power of distinguishing between these 

 indistinguishable masses, of attracting and being attracted 

 by those of its own kind, and of remaining indifferent and 

 neutral towards those of other kinds. 



That the pollen of an oak should not act on a daisy 

 seems to us natural ; that the naked protoplasm of these 

 minute organisms should be endowed with this selective 

 capacity does seem very remarkable, and may well make 

 one pause and think. Is it possible, one inclines to ask, 

 to feel sure that all the various species of myxies have been 

 produced from one original form by the force of a natural 

 selection ? How can the doctrine of the fittest be applied 

 as between two naked protoplasts, and if applied only to 

 the later stages of growth, how has it reacted on the earlier 

 stages ■? 



Classificatiox. — We now propose to deal with the classi- 

 fication of these organisms, and this will afford us an 

 opportunity of describing more in detail some parts of their 

 structure. 



The value of characters for the purposes of generic and 

 specific distinctions is a subject well worth consideration, 

 for it often reveals unexpected facts in the correlation of 

 parts, startling one by dividing organisms which, at 

 first sight, seem nearly akin. Colour is for the most part 

 of little value as a distinction in flowering plants, for 

 we know how widely colour will vary in the same species. 

 " Color," says Linnicus, " in eadem specie mire ludit : hinc 

 in differentia nil valet;" and yet in the pimpernel, the blue 

 and red forms differing in scarcely any other character are 

 true and not interchangeable species ; in the alga' the 



