11 FOEMATION OF SPOKES OF RHIZOPUS AND PHYCOMYCES. 



development of a new species of MortiercUa. Thougli the paper was 

 published very recently, little improvement over the older writers is 

 shown in the matter of technique. He has not. so far as he states, 

 made any sections of the sporangia. 



]^\ a study of entire sporangia he linds that the surface comes to be 

 marked out into polygons separated by rather broad bands of an even 

 width. These markings he interprets as representing a surface view 

 of pohdiedric masses of protoplasm which are destined to become 

 spores, separated by layers of intersporal protoplasm. 



Plasmolyzing agents in some cases cause the sporangium to contract 

 as a unit and not as individual polygons, showing that each is not 3'et 

 entirely surrounded ])y an osmotic membrane. 



Gentian violet stains the material between the polyhedrons: the 

 formation of the violet lines is progressive, as is shown by the fact 

 that in some cases they are short and do not extend over the entire 

 sporangium, but radiate from various points. In this. Bachmann makes 

 a decided advance over Leger, liut still he apparently fails to grasp the 

 most important point — that these blue-staining lines represent cleavage 

 furrows lilled with the stain. 



METHODS. 



The mold B/uzopux was tirst obtained in uiixed cultures by exposing 

 moistened bread for a few minutes to the air of the laboratory. To 

 ol)tain pure cultures, a few sporangia were carefully transferred from 

 the original cultures to slightly moistened bread, which had been 

 exposed an hour or so on two or more successive daj's to a temperature 

 of from 60- to 65^ C. in a steam sterilizer. In from one to two days 

 after inoculation the stolons began to appear on the surface of the 

 bread, and in another day there were a considerable number of 

 sporangia formed. 



The cultures of Phycomyces were obtained from Ann Arl^or, Mich. , 

 through the kindness of Dr. J. B. Pollock. This mold was grown 

 either upon sterilized bread or nutrient agar. From these cidtures 

 small bits of m3'celium were cut out (below the surface of the sub- 

 stratum in the case of PJiycomyces) and instantly immersed in the 

 hxing fluid. After remaining in this about twenty-fovir hours, they 

 were washed for a few hours in running water, dehydrated by run- 

 ning through grades of alcohol, cleared in xylol or chloroform, and 

 embedded in paraffin. 



The sections were cut on a Jung, or a lieinhold-Giltav microtome, 

 usually 4 /< thick, but sometimes 2 //, and were fastened to slides with 

 albumen and glycerine. They were then stained with Flemming's 

 triple stain (safranin, gentian violet, and orange G), then dehydrated, 

 cleared with clove oil or bergamot oil, and mounted in Canada bal- 

 sam. If the right exposures are given to these stains, the cytoplasm 



