Harper. — Cell-Division in Sporangia and A sci. 475 
the spore-plasm, though this is by no means involved in the 
description given by Biisgen. 
Recently Maurice Leger 1 has undertaken a very extended 
investigation of the cytology of a large series of Mucorineae. 
Leger points out the difficulties in technique which beset the 
investigation of the Mucorineae, and a careful reading of his 
paper is sufficient to convince one that the technical methods 
which he has employed are inadequate for overcoming these 
difficulties. A real insight into the cleavage phenomena was 
impossible from the preparations he was able to obtain. 
Leger himself is aware (p. 3-4) that there are very consider- 
able gaps in his account. 
Leger used alcohol for fixing, and cut sections in celloidin. 
In some cases he relied on results obtained from preparations 
of crushed sporangia. In my experience alcohol is a very 
unsatisfactory fixing agent for these materials, and not to be 
compared with those of Flemming, Merkel and Wilson. 
To his reliance on alcohol for fixing is probably due Leger’s 
inability to distinguish nucleolus and chromatin. He describes 
the nucleus as spherical, provided with a central nucleolus, 
which stains strongly, and a membrane; between the nucleolus 
and the nuclear membrane is a colourless zone which takes no 
stain. It is probable, judging from its relative size in his 
figures, that Leger’s nucleolus is a fused mass made up of 
nucleolus and chromatin together. Leger is convinced that 
the nuclei regularly divide by direct division, and that 
karyokinesis is only met with in the germinating spore. He 
does not tell us just how thick his sections cut in celloidin 
were. The difficulty of obtaining very thin sections in this 
medium may well have been responsible in part for his poor 
nuclear figures. 
Leger studied spore-formation in a very considerable series 
of forms from the genera Sporodinia , Mucor } Rkizopus , Chaeto - 
cladium , Thamnidium , Pilobolus , Pilaira , Mortierella , Syn- 
cephahs , and Piptocephalis. 
In Sporodinia the young sporangium is filled with homo- 
1 Leger, Rech. histol. stir les Mucorinees, 1897. 
