10 



KNOWLEDGE. 



January, 1913. 



and many of them are undoubtedly of cytoplasmic 

 origin (microsomata) ; a few of them are capable of 

 taking on certain stains, such as " neutral red " in 

 the living cell prior to any fixation, and after fixation 

 at least four types of granule may be distinguished 

 according to the manner in which these structures 

 stain. Thus there are to be found the so-called 

 neutrophilic granules (see Figure 15) staining with 

 neutral dyes (neutral red), the oxyphilic type (see 

 Figure 16) staining with acid dyes such as eosin 



and acid 

 b a sip hilic 

 Figure 17), 

 deeply with 

 stains such 

 blue ; and 

 times to be 

 phoph i I i c 

 staining 

 an acid or a 

 Many of the 

 ules seen in 

 plasm are, of 

 course, to be 

 p 1 a c e d 

 amongst the 

 category of 

 " metaplasm,' 

 granules of 

 protein, and 



fuchsin, the 

 granules (see 

 which stain 

 alkaline 

 as methylene 

 there are at 

 found am- 

 g r a n ules 

 with either 



Figure 15. 



A polymorphonuclear 

 neutrophile leucocyte from 

 human blood, showing mi- 

 nute neutrophilic granules 

 (represented too large in 

 figure). 



basic 

 larger 

 the 



dye. 



gran- 



c vto- 



FlGURE If). 



A coarsely granular oxyphile 

 leucocyte from human blood. 



pellicle, 



these being the various 

 reserve food (starch, 

 so on), and the plastids 

 are naturally quite distinct from the 

 small elementary structures noted 

 above. 



The Microsomata* mentioned above 

 usually exist upon the reticulum of 

 spongioplasm (where this can be 

 definitely stated to be present) and 

 stain as a rule with the acid dyes; the other 

 granules described are usually small rounded bodies, 

 varying in size from a quite distinct particle to a 

 fine granular appearance in the cell, the ultimate 

 granules being very indistinct (neutrophile type in 

 certain leucocytes). Such granules are, as a rule, 

 found scattered throughout the cell without any 

 definite relation to the spongioplasm network. 



Another type of granule remains to be mentioned, 

 and that is the one first described by Altmann 

 (Altmann's granules) ; these, which stain with 

 acid stains (acid fuchsin) after special treatment 

 with other reagents, are found in all animal and 

 plant cells with the exception of the ovum, the male 

 germ-cell, and cells forming cancerous growths. 

 They are assumed to possess an important role in 

 the cell economy ; but the precise nature of their 

 function is, I believe, still sub judice. 



Some of the granules mentioned above are looked 

 upon as possessing the capacity of manufacturing 

 enzymes in the cell, or may be the actual precursors 

 of the enzyme themselves ; the granules seen in the 



*The Microsomata are, it appears, chiefly concerned in the production of the cell-wall in plant-cells, a process akin 



secretion going on, which results in the deposition of cellulose. 

 +See " Knowledge and Scientific News," August-September, 1909. 



secreting cells of many glands, both in animals and 

 plants, are known to be zymogens and these granules 

 may be seen readily in the living cell. But the 

 function of many of the types noted is by no means 

 settled, and the study of them is perhaps one of the 

 most important branches of cytological work which 

 is being carried out at the present time in biological 

 laboratories. 



(h) Structure of the Nucleus. 



I have had occasion before in this magazine to 

 describe the structure of the nucleus in connection 

 with the mechanism of nuclear division, + and since 

 writing the article in which this occurred have 

 made further observations upon nuclear structure. 

 The results have gone to confirm the generally- 

 accepted description of the constitution of the 

 nucleus, viz., that this bod}' is to be looked upon as a 

 spheroidal space limited externally by a firm mem- 

 brane formed, in all probability, of altered hyaloplasm 

 (kinoplasm), this space being filled with clear 

 nucleohyaloplasm, suspended in which latter is a 

 network of linin, and in the resting 

 nucleus the granules of chromatin 

 are arranged upon this network at 

 somewhat irregular intervals (see 

 Figure 18). With regard to the 

 presence of a nuclear membrane, a 

 somewhat controversial point, the fact 

 that the nucleus moves bodily along in 

 the endoplasm during the phenomenon 

 of " rotation " in the living assimilat- 

 ing cells of plants {Vallisneria , Elodea , 

 and so on) without any alteration of 

 shape, seems to point to the possession 

 of an external firmer delimiting 

 quite distinct from the 

 cytoplasm of 

 the cell. The 

 nucleoli (plas- 

 mosomes) ap- 

 pear also to 

 have an exter- 

 nal skin, within 

 which the fluid 

 parts of these 

 bodies is con- 

 tained. 



Further re- 

 search by cyto- 

 logists has 

 pointed to the 

 presence of fine 

 fibrils passing 

 from nucleus to 

 nucleus in adjacent protoplasts; it will be remem- 

 bered that distinct intercytoplasmic connecting 

 bridles have long been demonstrated passing between 

 adjacent cells (Gardiner and others : see Figure 19) 



Figure 17. 



A coarsely granular basiphile leuco- 

 cyte from human blood (very rarely 

 found.) 



[Note. — This and the previous two figures are 

 from coloured diagrammatic drawings from a 

 hlood film made by the author.] 



