562 SUMMARY OF CURRENT RESEARCHES RELATING TO 



metal salts was used, and their influence on the development of the 

 fungus was noted. The form of the mycelium was largely affected ; it 

 became multi-septate, and often a cell complex was built up. Opaque 

 shining plasma masses also filled many of the cells. These as well as 

 the newly-formed septa consisted of pectin. By plasmolysing the 

 kyphas, the same effects were produced, and the septa and plasmic 

 masses were formed in the hyphaa. Normal sporangia and zoospores 

 were formed when there was a dearth of nutriment. A weak metal 

 solution, or a slight plasmolysis, induced intercalary sporangia! growth, 

 and the plasma masses occasionally were transformed into sporangia. 



Change of form was also observed in the oogonia and oospores. The 

 oogonia in most of the culture media had smooth walls ; when grown 

 in cane- or grape-sugar, they had ornamented walls, were very large, and 

 of somewhat oval form. Considering these variations, the alteration 

 and correcting of the diagnoses that have been given of the species of 

 Sa prole;.; nlaceae is very necessary. The author gives descriptions of two 

 new sptcies discovered by him during his research. The first, which he 

 calls Achlya oidiifera, was distinguished by the hyphaa breaking up into 

 oidium-like cells. In pure water these " oidia " formed zoospores ; in a 

 culture medium they grew out into hyphse. The species formed oogonia 

 in the interior of ants' eggs, but antheridia could not be detected. 

 Oogonia were not formed in any of the artificial cultures. In contrast 

 to this species, the other, A. Saprolegnia, formed abundant oogonia and 

 antheridia terminal on lateral branches of the hyphaj. The branchlets 

 often formed a short spiral, and on this account the name 8. retorta was 

 given to the species. Sporangia were formed when the mycelium was 

 placed in pure water. Tables are given of the different reagents used, 

 and of their effect on the vegetative and reproductive organs, and a 

 bibliography of the works bearing on the subject is added. 



Zygospore Formation in Mucoraceas.*— A. F. Blakeslee has found 

 by experiment that there are two kinds of Mucoraceae ; those like 

 8porodinia, that form zygospores on the filaments of one plant, 

 which he designates homothallic ; and those in which zygospores are 

 produced only by the copulation of hyphae from two different strains. 

 These, which include most of the Mucors, he terms heterothallic. He 

 thus explains the difficulty so often experienced of inducing the forma- 

 tion of zygospores. This fact confirms the opinion " that the formation 

 of zygospores is a sexual process ; that the mycelium of a homothallic 

 species is bisexual ; while the mycelium of a heterothallic species is uni- 

 sexual." The writer promises further investigation. 



(Edomyces leproides.f— This fungus, elsewhere published as Chryso- 

 phtyctis endobiotica, forms the subject of a leaflet issued by the Board of 

 Agriculture. It causes a disease of potato tubers, but does not attack 

 turnips, carrots or cereals. The presence of the fungus is made known 

 by the stimulating influence it exerts on the tubers, causing irregular 

 outgrowths of a blackish colour. Experiments were conducted at Kew 

 to test the mode of infection, and the best means of preventing the 



* Science, n. s.. xix. (1904) pp. 864-G. 



t Board of Agric. and Fisheries, leaflet No. 105. 



