FUNGI. ZYGOMYCETES. 91 



into which the mycelium finds its way. Mticor stolonijer covers in a short time 

 large patches of the like substrata, the mycelium forming long stolon-like branches, 

 which fix themselves root-wise at their extremities and form gonidiophores with small 

 black heads. The mycelium has been known to penetrate the shell of a freshly laid hen's 

 egg and form gonidial capsules in its air-space. Phycomyces nitens is known by its 

 violet-coloured gonidiophores which are from ten to fifteen centimetres in height. 

 The genus Thamnidium forms an ordinary capsule at the top of its tall gonidiophore, 

 and lower down whorls of small branches with small capsules containing only a few 

 gonidia. The genus Pilobolus is almost certain to make its appearance if fresh horse- 

 dung is put under a glass cover. 



b. The CHAETOCLADIEAE. The genus Chaetocladium is parasitic on Mucor. If the 

 germ-tubes from the gonidia of Chaetocladium encounter a filament of Mucor, they 

 form an open communication with it and develope at the point of union a cluster of 

 branches, some of which grow on into other mucor-filaments, while others form organs 

 of propagation. The gonidia in this case, as in the following sub-family, are not formed 

 in a sporangium (gonidangiuvi) but by abjunction. The gonidiophores form whorls of 

 branches, and some of the lateral branches swell out and form on their surface slender 

 protuberances (sterigmatd), and from the apex of each of these a gonidium is 

 abjointed. The formation of the zygospore is as in Mucor. 



c. The PIPTOCEPHALIDEAE are distinguished by the circumstance that the young 

 zygospore developes at a distinctly defined and localised growing-point which soon 

 disappears, and a simple process of division then takes place (Brefeld). The 

 point of union of the two conjugating cells bulges outwards, the convexity quickly 

 enlarges into a spherical form, and the mass of dense protoplasm moves into it. Then 

 the curved posterior part of the zygospore (Fig. 55, s) is cut off from the spherical 

 portion, which is now the resting spore of the Fungus (Fig. 55, Z.) Piptocephalis is 

 parasitic on Mucor ^ and is represented in detail in Fig. 55. 



The small group of the ENTOMOPHTHOREAE is allied to the Zygomycetes 1 . These are 

 parasites on living animals, which they usually kill in a short time. The only two 

 genera are Empusa and Entomophthora ; resting-spores are known in the latter, and 

 these, according to Nowakowski, are the result of conjugation. 



Empusa. The best known species is Empusa muscae, which is often the cause 

 of an epidemic among houseflies in autumn. The Fungus rapidly multiplies its cells by 

 sprouting, after the manner of the Yeast-fungus, in the fatty substance of the fly and 

 thus kills it. Then the isolated cells put out tubes which pierce through the skin 

 of the fly, and form gonidia by abjunction from their extremities in the open air, 

 one from each filament. These gonidia are abjected with some force, and when one 

 alights on the lower side of the hinder parfbf the fly's body it can penetrate through 

 its skin and infect the whole insect. Usually, however, the gonidia, smeared with 

 a sticky substance obtained from the protoplasmic content of the ruptured gonidiophore, 

 light first when abjected in the neighbourhood of the spot where the infected fly 

 has fixed itself, and there give rise to secondary gonidia which are also flung oft 

 with force. The gonidia in this case form a white deposit in the neighbourhood of 

 the dead flies. Resting-spores are not known in Empusa, but they are found in the 

 next genus. 



Entomophthora attacks various insects and their larvae ; the best known is 

 E. radicans, which in some years causes an epidemic in the caterpillars of the 

 cabbage-butterfly. In this case too the gonidia put out germ-tubes which pene- 

 trate the skin of the caterpillar ; but the further development in the body of the 



1 Brefeld, Unters. liber d. Entw. d. Empusa muscae u. E. radicans (Abhandl. d. naturf. Ges. 

 zu Hall, XII Bd., where older literature on the subject is given) ; Id. Unters. iiber d. Schimmelpilze 

 IV. Heft, p. 97, {Entomophthora radicans}; [also Untersuch. aus d. Gesammtgebiete d. Mykologie IV. 

 (1884) Entomophthoreen] . Nowakowski, Die Kopulation bei ein. Entomophthor. (Bot Zeit. 1877, 

 p. 217). [See also De Bary, Vergl. Morph. \\. Biol. d. Pilze. Mycet. u. Bacterien, Leipzig 1884.] 



