STRUCTURAL BASIS OF THE CELL 213 



the reagents, as Fischer's experiments suggest ? Or are they normal 

 and constant morphological elements that have a definite significance 

 in the life of the cell ? It is certain that the microsomes are not 

 merely nodes of the network, or optical sections of the threads, as 

 the earlier authors maintained ; for the fibrillae may often be seen to 

 consist of regular rows of granules. Van Beneden gave the first 

 clear description of the microsomes in this regard in the following 

 words : " I have often had occasion to note facts that establish the 

 essential identity of the moniliform fibrillas and the homogeneous 

 fibrillae of the protoplasm. In my opinion every fibrilla, though it 

 appear under the microscope as a simple line devoid of varicosities, 

 is formed at the expense of a moniliform fibril composed of micro- 

 somes connected with one another by segments of uniting fibrils." ^ 

 Again, in a later work he says of the fibrils of the astral system in 

 Ascaris : "It is easy to see that the achromatic fibrils are monili- 

 form, that they are formed of microsomes united by inter-fibrils." ^ 

 Similar observations have been made by many later writers. In the 

 eggs of sea-urchins and annelids, which I have carefully studied, there 

 is no doubt that after some reagents, e.g. sublimate-acetic, picro- 

 acetic, chromo-formic, the entire astral system has exactly the struct- 

 ure described by Van Beneden in Ascaris. Although the basal 

 part of the astral ray appears like a continuous fibre, its distal part 

 may be resolved into a single series of microsomes, like a string of 

 beads, which passes insensibly into the cytoreticulum. The latter is 

 composed of irregular rows of distinct granules which stain intensely 

 blue with haematoxylin, while the substance in which they are em- 

 bedded, left unstained by haematoxylin, is colored by red acid aniline 

 dyes, such as Congo red or acid fuchsin. 



The difficulty is to determine whether this appearance represents 

 the normal structure or is produced by a coagulation and partial dis- 

 organization of the threads through the action of the reagents. A 

 justifiable scepticism exists in regard to this point ; for it is perfectly 

 certain that such coagulation-effects actually occur in the proteids of 

 the cell-substance, and that some of the granules there observed have 

 such an origin. It is very difficult to determine this point in the case 

 of the cyto-microsomes, owing to their extreme minuteness. The 

 question must, therefore, be approached indirectly by way of an 

 examination of the nucleus and its relation to the cytoplasm. Here 

 we find ourselves on more certain ground and are able to make an 

 analysis that in a certain measure justifies the hypothesis that the cyto- 

 microsomes may be true morphological elements having the power of 

 growth and division like the cell-organs formed by their aggregation. 



1 ^%Z> P- 576, 577- ■' '87- P- 266. 



