Wilson. — Spermatogenesis in the Bryophyta . 451 
in spermatocyte I. These chromidia persist in spermatocyte II, and in the 
spermatid give rise to a triangular or polyhedral body, the 6 Nebenkern ’. 
This, together with a plasma mass, is thrown off finally from the sperm. 1 
Von Baehr (4) in Aphis Saliceti states that after the final division of the 
spermatocytes a 1 Nebenkern ’ in the form of a ‘ Blaschen ’ with stainable 
walls appears. This probably originates from the mitochondria. Later on it 
becomes shaped like a split ring, and finally disappears during the forma- 
tion of the sperm. Wasilieff (72) states that the mitochondria found in the 
spermatocytes of Blatta germanica originate from the nucleus. 
A consideration of the above results leads to the conclusion that the 
limosphere bears a close resemblance to the ‘ Nebenkern ’ described in several 
animal spermatids, and that at least in some cases the two have a similar 
origin. It is not desired, however, to state that the two structures are 
homologous. At present little evidence is available as to the occurrence 
and formation of the limosphere in plants, and such a generalization would 
not be justified. The elimination of chromatic material from the nucleus 
during spermatogenesis seems to be almost universal in animals and plants. 
The widespread nature of this phenomenon suggests that it is of far- 
reaching importance. It is possible that some such separation of material 
must take place before the cell can undergo the changes which result in the 
formation of the sexual cell. The material eliminated probably differs 
considerably in composition from the cytoplasm which surrounds it, and 
during the chemical changes which take place after its separation from the 
nucleus it is not surprising that structures of more or less constant form are 
produced. The appearances already described, which are seen during the 
formation of the limosphere, strongly suggest that the material of which it 
is formed is gradually changing in composition, so that finally the greater 
part of it loses its capacity for taking up the nuclear stain. A similar 
elimination of chromatic material takes place in many plants during the 
formation of the egg. An instance of this in the Musci has been given by 
Holferty (29), who states that masses of chromatic material are present in 
the cytoplasm of the egg of Milium cuspidatum . 
The extrusion of chromatic substance from the nucleus during meiosis 
is a widespread phenomenon in plants. 2 Miss Digby (21) has recently 
given an account of the extrusion of bodies from the nucleus at this stage 
in Galtonia candicans , and a considerable number of examples of this 
process are here quoted. It is a highly suggestive fact that at two im- 
portant stages in the life of the organism chromatin is eliminated from the 
nucleus, while during the intervening periods little or none is thrown out. 
1 Popoff’s results have been adversely criticized by Murray, Ancel, and Bolles Lee. These 
investigators admit the existence of the chromidia but question their nuclear origin. 
2 Since in animals meiosis always coincides with the maturation of the sexual cells, the two 
periods during which extrusion of chromatic material from the nucleus takes place in plants cannot 
be here distinguished. 
