476 Harper. — Cell- Division in Sporangia and Asci. 
geneous protoplasm in which the nuclei multiply rapidly by 
direct division. He notes nothing in the cutting off of the 
columella, except that the plasma is divided into an outer 
denser sporogenous part, and an inner less dense part with 
fewer nuclei about which the columella-wall is laid down. 
For the formation of the spores Leger quotes Van Tieghem’s 
account, with the correction that the nuclei are continuously 
present during the process. He accepts the doctrine that the 
cleavage of the spore-plasm is due to a differentiation into 
a granular portion, which condenses itself into polyhedric 
masses which gradually round themselves up, and a hyaline 
intersporal plasma which fills the spaces between the poly- 
hedric masses and forms a continuous layer beneath the 
sporangium-wall. The spores are formed by a process of 
free formation, and enclose themselves in a cellulose-wall by 
secretion from their surfaces. The masses are separated 
simultaneously, and Ldger figures the separating zones of 
intersporal substance as being plates of equal thickness 
throughout. It is hard to see how he could have failed to 
observe the furrows which cut into the protoplasm gradually 
from the surface, and which can be observed readily on living 
material with an ordinary lens. 
Leger studied the sporangia of Mucor Mucedo , and the 
remaining forms with large sporanges, at the stage of spore- 
formation, chiefly by means of crushed specimens and optical 
sections, and concludes that the process is the same as in 
Sporodmia, a differentiation of the plasma into polyhedric 
spore-bodies and intersporal substance which separates them. 
In Rkizopus nigricans he notes a stage where the poly- 
hedric masses are formed before the intersporal substance 
appears, and says he has not observed this elsewhere. In 
Mucor racemosns the plasma cleaves into sporogenous poly- 
hedric bodies containing three to seven nuclei. In small 
sporangia with few spores, each contains a larger number of 
nuclei than do the more numerous spores in larger sporangia. 
The remaining forms investigated show nothing especially 
characteristic in their method of spore-formation. 
