Olive. Mitotic di vision of tlie nuclei of the Cyauophj^ceae. 35 



bodies lying witliin a delicate network. He eniployed this 

 inethod, in fact, to assist in proving the nuclear natura of the 

 central body. Fischer, on the other hand, contends that such 

 an appearance as that shown, e. g., in hg. 31, is due solely to 

 „enzymatische Kontraktion", and that no digestion whatever 

 occurs. 



In my experiments , filaments of Osc'illaforia Froelichia and 

 other fornis were allowed to remain two or three days, at about 

 33^^ — 36° Cent., in a preparation of Clrübler's pepsin; the 

 masses were then washed in water, fixed, carried throiigh the 

 paraffine process, and sectioned. Fig. 20 ilkistrates a cross 

 section of OsciUaforia thus treated, which is drawn to the same 

 Scale as the sections of the same species shown in figs. 24 and 

 25. A comparison of the digested with the undigested sections 

 will at once show that either considerable digestion has taken 

 place, or eise a very large amount of „enzymatische Kontrak- 

 tion". Fig. 19 is a longitiidinal view, also treated with pepsin. 

 In both transverse and longitudinal sections, we can see all the 

 parts of the protoplasni which we have previously noted in the 

 untreated sections — chromatophore and chromatin, as well as the 

 dimly defined achromatic portion of the nucleus. The assertions 

 of Hegler and Kohl that the cyanophycin granules are digested 

 was confirmed; and, fnrther, the statement of Kohl that neither 

 pepsin nor pancreatin will digest the slime globales, is also 

 probably triie. It is a much more difficult question as to whether 

 any of the protoplasm itself is so affected. The writer, however, 

 lii'mly believes that some digestion of the protoplasm does occui^, 

 and he bases such a conclusion mainly on the fact, perhaps 

 insufücient in itself, that there is not apparent in the normal 

 cell of OsciUaforia enough vacuolar space to account for such 

 an enormous slii'inkage of volume, through simple plasmolysis 

 alone. 



Summary of results and coiicliisioiis. 



1. The central body of the Cijanophyceae is a nucleus, not 

 essentially different from the nucleus of the higher plants. It 

 consists of a more or loss dense, librous, achromatic portio, and, 

 cnclosed by this, a number of minute, globular, or somewhat 

 irregularly shaped chromatin granules. The chromatic and 

 achromatic substances stain with the Standard nuclear stains, 

 0. g., iron haematoxylin and Flemming's triple stain, similarly 

 to the corresponding elements of higher plants (pp. 17 — 24). 



2. In the opinion of the writer, thin, well stained sections, 

 made in both transverse and longitudinal planes, are necessary 

 for the thorough study of the nuclear structure of these organ- 

 isms. 



3. The nucleus of the Cyanopliyccao usually appears to be 

 in a State of mitotic division. Plants which were subjected to 

 slow desiccation until thoroughly dried showed no perceptiblo 

 indication of entering a resting condition (p. 26.) 



3* 



