ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 343 



been made on this genus of Entomophthoreae, especially by Cohn, 

 Brefeld, and Thaxter. He was fortunate enough to find a small fly 

 belonging to the genus Sciara on some horse-dung cultures in the 

 laboratory which was attacked by a species of Empusa. He got a large 

 series of the insects representing every stage of the life-history of the 

 fungus, and the description of the new species E. Sciam is the main 

 subject of the paper. The fly lays its eggs on the surface of the dung 

 or on the sides of the vessel, and infection must take place at a very 

 early stage in the life of the insect, as adult larvse were not induced to 

 take the disease. If the cultures were kept moist the majority of 

 infected individuals died at the larval stage. If the conditions were 

 drier the adult fly, even when attacked, was developed, and only died of 

 disease after ovipositing. Olive found the earliest stage of vegetative 

 hyphas in the larvaa. At first they were multinucleate and non-septate, 

 then, later, septa were formed and the body-cavity became filled with 

 hyphas. The fructifying stage occurs on the death of the insect. 

 Rhizoidal hyphae are formed which attach the insect to the substratum, 

 and conidiophores, simple or branched according to the species, rise from 

 the vegetative hyphae. These bore their way through the tissue of the 

 host and produce conidia at the apex. In some species the ccenocytic 

 conidiophore divides up into uninucleate cells, and the conidium also is 

 uninucleate. In Empusa musca, where thei conidium is multinucleate, 

 only one septum is formed in the conidiophore immediately below the 

 conidium. The resting-spores — zygospores or azygospores — are formed 

 on larger hyphae. Olive describes also the abjection of the conidia. 

 The process is somewhat similar to that described for the sporangium of 

 Pilobolus. 



Study of Saprolegniese.* — Paul Dop has tested the influence of 

 certain substances on the development of Saprolegnia Thureti, the 

 parasite of fishes. If the conditions are anaerobic the hyphae are more 

 slender, the older parts more septate, and the grains of cellulin are 

 smaller. Carbon can be supplied to the fungus as glycogen. In mineral 

 solutions there is no cellulin formed and growth is slow, while the septa 

 are numerous. 



Fertilisation in Mucorini.f — Dangeard gives an historical sketch of 

 our knowledge of this subject. He then draws attention to the fact 

 that in conjugation in this group of fungi we have the union of garne- 

 tangia. He followed the process more especially in Jtfucor fragilis, and 

 noted the union of a number of nuclei, the mature zygospore con- 

 taining many fused nuclei which provide those of the new thallus. 



Witches' Broom on Cherry. J — Emil Heinricher considers that the 

 deformations caused by Exoascus Cerasi are favourable objects for 

 studying physiological phenomena. He transferred the disease from one 

 tree to another by grafting, and found that spontaneous infection by 

 spores is of rare occurrence. 



* Bull. Soc. Bot. France, lii. (1905) pp. 156-8. 

 t Comptes Rendus, cxlii. (1906) pp. 646-7. 



t Naturw. Zeitschr. Land. Forstw., iii. (1905) heft 8, pp. 344-7 CI fig.). See also 

 Hedwigia, xlv. (1906) Beibl., pp. 106-7. 



