HISTORICAL. 1 1 



inclined to accept the view of Fischer (1892), which is that in .such 

 forms as Si/iteejf/ia/is the spores borne in a sinole row an* formed 

 exoo-enouslv by constriction like conidia. the wall of the fruitino- 

 body forming part of the spore wall, and that this body can not, 

 therefore,, be considered as a sporangium homologous with that of 

 Jfiteof. After a thorough stud}' of Syneephaliutruni and Si/ncej?/talls, 

 however, he accepted the "sporangial" theory, and brings very con- 

 clusive evidence to support his results. In Sytivejfhalastruni race- 

 mosum he iinds that the contents of the CA'lindrical cells that are to 

 form the chains of spores are divided into spores, not b}' gradual con- 

 striction from the surface inward. l)ut sinudtaneously b}' a hyaline 

 intersporal sul)stance. Walls art* then formed ai'ound the individual 

 spores entirely within and distinct from the wall of the mother cell. 

 By crushing these spore rows under a cover glass he was able to force 

 the spores out in a perfect condition, leaving the walls of the sporangia 

 empty and intact except for their ruptured tips. This is conclusive 

 evidence of the* endogenous formation of these spores. Furthermore, 

 in many cases he tinds that the spores are borne, not in single rows, 

 but more or less irregularly, the diameter of the sporangium being 

 somewhat great»M- than that of a single spore. In such cases the 

 planes of separation are obli([ue, or even parallel, to the long- axis of 

 the sporangium. In such a form as this Thaxter tinds an inter- 

 mediate stage between the spherical sporangium of Mucor and the 

 cylindrical one of Syncejyhalis^ the supposed ab.sence of which was 

 used by Fi.scher as evidence against the homology of the two. 

 • In S'l/ncejjhalis, Thaxter tinds that the separation of the protoplasm 

 into spores is quite different from that in Si/nee/jhalastnwi. He 

 investigated an undescribed species from Li})eria, and also S^yncepludh 

 'pycnoHperma^ and tinds that in both cases the protoplasm is cut pro- 

 gressively from the .surface inward V)y '"intermediary zones," each of 

 which is made up of an inner nonstainal)le part, and an outer one that 

 takes stains readily. The spore wall in both species is distinct from 

 the sporangium wall and forms close around the protoplasm, exclud- 

 ing the intermediary zones. In the undescribed species the.se zones 

 remain until the spores are ripe and then deliquesce, while in Syn- 

 cejyJtdl is pyenos2>erma the stainable portion breaks up into a refractive 

 oily substance and the nonstainable part forms a thick permanent 

 layer around the spore Avail and gives to the spores their peculiar 

 shape. 



Harper (1899) has described the spore formation in PUoholus and 

 Sporodinia of the Mucorinese, and also in Synchltrium of the Chytri- 

 diaceffi. The processes in these widely separated forms show many 

 interesting points of similarity. 



In Synchitriuin, Harper finds that the " initial cell" contains at first 

 one comparatively large nucleus, which, as the cell reaches nearly its 



