110 CARNEGIE INSTITUTION OF WASHINGTON. 



half-hourly, hourly, and eventually at less frequent intervals showed 

 that viable spores disappeared from the blood-stream in about 48 

 hours, but no more rapidly in No. 5 and No. 55 than in the control 

 animals that had not previously been treated. A similar experi- 

 ment was performed with mixtures of spores with the sera of the 

 treated rabbits in vitro and confirmed the conclusion that rabbits 

 are incapable of forming an antibody in the blood which will dissolve 

 these mold-spores. They are capable, however, of producing cyto- 

 lytic antibodies that will dissolve red blood-corpuscles and certain 

 other animal cells, and it was hoped a similar cytolysin might be 

 developed for spores and that the action might be sexually specific. 

 In attempting to use the ordinary bread mold {Rhizopus nigricans) 

 in getting immunity reactions with rabbits they discovered that this 

 common species is extremely poisonous. The extract from 0.04 gm. 

 of dried filaments is sufficient to kill a 3-pound rabbit. The toxin 

 which has been obtained by Dr. Gortner by precipitation with alcohol 

 resists peptic digestion, also the action of boiling temperature at 

 least for 5 minutes. It is therefore not a tox-albumen. It is soluble 

 in water, but is non-dialyzable. The minimum fatal dose intraven- 

 ously is about 1 part to 225,000 parts of rabbit by weight. The 

 enormous strength of the Rhizopus toxin may be shown by a com- 

 parison with some recently investigated organic toxins. White and 

 Avery have found that the minimum fatal dose of the poisonous 

 substance from the tubercle bacillus is one part to 15,000 parts of 

 body-weight, while the toxic cleavage product from edestin kills in 

 doses of 1 part to 40,000 of body-weight. Alsberg's penicillic acid, 

 isolated from Penicillium, has a minimum fatal dose in subcutaneous 

 injections of 1 part to 4,700 of body-weight. The toxicity of the 

 Rhizopus poison appears, therefore, to be 5.5 times that of the 

 tubercle bacillus, 15 times that obtained from edestin, and 45 times 

 that of penicillic acid. Dr. Blakeslee has previously made a special 

 study of the distribution of Rhizopus and finds it occurs throughout 

 the world and is almost certain to appear as a spontaneous infection 

 of bread and similar substrata rich in carbohydrates, whenever the 

 proper temperature and moisture requirements are observed. Its 

 possible relation to those diseases of unknown origin, such as pellagra 

 and the horse-disease and the corn-stalk disease of the middle west, 

 which have been attributed to infected food, is not being overlooked. 



THE MODIFYING EFFECTS OF CAVE CONDITIONS. 



Dr. A. M. Banta's experiments with cave material are being con- 

 tinued. The mud minnows (Umbra limi) are showing some further 

 depigmentation; Camharus hartoni, a non-cavernicolous crayfish, 

 likewise shows a progressive loss of pigment; some of the salamander 

 larvae in the cave during the present year have less pigment thao 



