100 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mycctcs ; II. Gymnoascus, Disconiycctcs (Discoliclicucs, Pyrcno- 

 liclicnos), ryrciiomycctes, Pcrisporiacei, Tuberacei ; III. Plasmodio- 

 phora, Myx'oinycctcs, Cliytriiliaccfc, (1) Saprolegiiie89, Monoblepha- 

 ridcaa, (2J Pcronosporcw, (8) Mucoriui. 



Fungi Parasitic on Aurantiaceae.* — O. Pcnzig has paid further 

 attention to the fungi parasitic on oranges and citrons in Italy, and 

 especially on those growing in the open air, which he finds to bo 

 attacked by the same kinds as those grown in orangeries. He adds 

 13 fresh species to those already described, making in all IGG. 



" Cancer" of Apple-trees.f — E. Gothe has afresh investigated the 

 cause of the so-called " cancer " of apple-trees, both that form of the 

 disease in which the wounds still remain open, and that in w'hich 

 they are closed into tuberous outgrowths. In all cases he states that 

 true cancer — distinguished by concentric rings round a central point, 

 the death of the bark, and a conspicuous open wound — is always the 

 result of the attacks of the parasitic fungus Nectria cUtissima. 



Conidiobolus, a new genus of Entomophthoreae.| — 0. Brefeld 

 has observed a fungus to which he gives the name Conidiobolus 

 utriculosus, growing as a parasite on cultures of Tremellini, and 

 frequently going through all stages of development in the course of 

 a single day or night. The spores or conidia are of a pear-shaped 

 form, about • 05 mm. long by • 035 mm. broad. The germinating 

 hyphfB proceeding from them give rise to secondary, and these again 

 sometimes to tertiary conidia. All the conidia are characterized by 

 the force with which they are thrown off when detached. When sown 

 in nutrient fluids the conidia give rise to a copiously branched my- 

 celium, which carries on the vegetative existence for a considerable 

 period, and then has the faculty of breaking up by fragmentation 

 into a number of detached pieces, as in the other Entomophthorcas, 

 on which abundance of reproductive branches are produced. 



The production of conidiophores is preceded by the appearance of 

 septa in the hyphfe ; their length varies considerably ; but they have 

 always a great tendency to bend towards the light. 



The reproduction of Conidiobolus by means of conidia goes on for 

 a number of generations, when the production of resting-sporos 

 begins, developing from protuberances in the mycelium. These pro- 

 tuberances grow into thick tubes which conjugate with one another. 

 Before conjugating the apices of both tubes swell up, but one much 

 more than the other, the contents of the smaller one passing entirely 

 into the larger one, and thus giving rise to the resting-spore, the 

 diameter of which is on the average about • 08 mm. The wall of 

 the resting-spore becomes finally differentiated into a thin yellowish 

 warty exospore, and a three or four times thicker endospore. They 

 begin to germinate in about ten days. The peculiarity in the con- 



* Atti R. 1st. Vcneto, ii. (1S84). SeeBot. Ctntralbl., xix. (1884) p. 1G3. Cf. 

 this Journal, iii. (1883) p. 539. 



t Bot. Ztg., xlii. (1884) pp. 385-9 (1 pi.). 



X Brefeld, O., 'Uutcrs. aus d. Gesumuitgob. dor Mykologie,* Heft 6, pp. 35-78 

 (3 pU) Leipzig, 1884. 



