404 Eumycetes. 



denburg bearbeitet wurden, begannen noch im 2. Heft die niede- 

 ren Eumycetes von M. v. Minden zu erscheinen. Das 3. Heft 

 bringt die Fortsetzung derselben und zwar den Schluss der 1. Reihe 

 (Chytridiineae), die 2. und 3. Reihe {Ancylistineae und Monoblephari- 

 dineae) sowie den Anfang der 4. Reihe [Saprolegniüieae). 



W. Herter (Porto Alegre). 



Melhus, I. E., Experiments on spore germination and 

 infection in certain species of Ootnycetes. (Univ. Wisc. Ag. 

 Expt. Sta. Res. Bull. XV. p. 25-91. pl. 1-10. Jun. 1911.) 



In this well-done piece of work a review of the earlier work 

 on the germination of such spores as the conidia of Albugo and 

 other species of Oomycetes is followed by a report upon the expe- 

 rimental studies conducted at the Universit}'^ of Wisconsin. The 

 results of numerous experiments are portrayed in the form of exten- 

 sive tables which are later discussed in considerable detail. The 

 leading problems considered were: the conditions that influence 

 the germination of the conidia of Cystopus candidus; conditions 

 influencing infection; and, the occurrence of socalled physiological 

 species of C. candidus on the various crucifers. The author found 

 that the conidia germinated at strikingly low temperatures rather 

 than at high temperatures. The Optimum temperature for germination 

 seemed to lie near 10 degrees C. The minimum was very near 

 zero, while, as de ßary has shown, the maximum was about 25 

 degrees C. It was found that water was the most favorable medium 

 for germination, and that no germination occurred upon various 

 nutritive culture media. Zoospores escaped as a rule in less than 

 ten hours, the time varying from two to ten hours. The shortest 

 period in which germination was observed was 45 minutes. Envi- 

 ronmental factors, host vitality and season seemed to influence the 

 time required for spore germination, and furthermore these factors 

 seemed to vary with the season. Light seemed to have no effect. 

 The conidia germinated as readil}^ in a non-saturated atmosphere 

 as in a saturated atmosphere. 



Chilling was found to exercise a very marked effect on the 

 degree of infection secured. Ninety-five percent of the seedlings 

 that had been chilled became infected while the controls usually 

 showed less. than 5 per cent of infection and never more than 5 

 per cent. The writer concludes that the favorable effect of chilling 

 on the conidia of Cystopus is plainly an adaptation to the environ- 

 ment of the fungus. The fall in temperature that leads to the depo- 

 sition of dew is of advantage not only in providing a means of 

 transport of those zoospores that escape from the germinating conidia 

 but the same decrease in temperature also stimulates the germi- 

 nation of the conidia. This work showed that sickly host plants 

 were not so easily infected as healthy ones. Some evidence was 

 obtained that indicates the possible presence of a number of phy- 

 siological species within the forms studied in this paper. 



R. J. Pool. 



Murrill, W. A., lUustrations of Fungi. X. (Mycologia IV. 

 p. 1—6. 1912.) 



The foUowing species are represented in a color plate in this, 

 the tenth series on the same subject by Dr. Murrill: Hypholoma 



