ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 279 



all essential points, of the dermatopliytes whicli acconapany different 

 infectious diseases, as well ag their apparent identity with the 

 milk-ferment, Oidium lactis. He had also given reasons, derived from 

 a number of careful experiments, for believing that these fungi were 

 not true parasites, but partook more of the nature of saprophytes. 

 More recent exj)eriments by Groh3 and Block appeared to lead to 

 an opposite conclusion ; and Dr. Grawitz is not able to offer an 

 explanation of these apparently contradictory results. 



The two most widely distributed and best known of the fungi in 

 question, Aspergillus glaucus and Penicillium glaucum, each occur in 

 two different forms which present no morphological difference, but 

 which differ very widely in their physiological properties. The one 

 (sa^jrophytic) may be introduced into the blood of the higher animals 

 without showing any disposition to germinate ; the other (parasitic) 

 germinates and spreads with the greatest facility, and is eminently 

 pathogenous. Both forms may be produced from the same original 

 stem, and each form may be reproduced through from twelve to 

 twenty generations, and may then give birth to the other. The 

 malignity of the pathogenous form depends on the entrance of the 

 spores into the blood, where they germinate, and then pass with great 

 rapidity into the various tissues of the body, where they cause local 

 necrosis. 



Spore-diflfiision in the larger Elvellacei.* — Mr. C. B. Plowright 

 describes the result of some observations on about 100 specimens 

 of Morchella gigas Pers. In the evening, as the rays of the setting 

 sun fell obliquely upon them, he observed that all the older speci- 

 mens were quietly and continuously diffusing their sporidia. Each 

 sporidium was distinctly visible to the naked eye, floating in the 

 air, twisting and turning in the sunlight. The head of each of 

 the morells was surrounded by a cloud of sporidia extending 3 or 

 4 inches above and around it. This cloud could only be seen in 

 the oblique light against a dark background. When acted upon by 

 a gentle current of air, such as would be produced by gently waving 

 the hand, it swayed to and fro without manifesting any tendency to 

 become dispersed. The comjionent sporidia were in constant motion, 

 rising and falling, and circling about, as if there was no law of gravity. 

 When the cloud was blown quite away by a more powerful air-current, 

 it in the course of a few seconds re-formed. The contents of each 

 ascus could be seen to be separately ejected in a minute jet, consisting 

 of a limited number of sporidia, which speedily became lost with the 

 others forming the cloud. 



The phenomenon is, he considers, interesting from a physiological 

 point of view, as showing the capabilities of the unaided human eye. 

 These sporidia measured only about one-hundredth of an inch in their 

 long diameter, and five one-thousandths of an inch in their short, 

 yet they could distinctly be seen to be bodies having length and 

 breadth. 



What particularly struck him when observing these spores being 



* 'Grevillea,' ix. (ISSO) pp. 47-8. 



