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never leaves its burrow ; but if a pustule should be formed above 

 it, by the scratching of the patient, the larvse are destroyed ; but 

 the mother cunningly emerges to the surface at the edge of the 

 pustule, and commences a downward descent anew. The male is 

 much smaller than the female, and has ten extremities. The 

 female wants one of these posteriorly, and the young three. She 

 is also armed with two saw-like claws, which cut a way through 

 the tissues by a transverse motion over each other as the blades 

 of scissors do. Hebra thinks the opening for the exit of the 

 eggs is a fold or valve on the belly, which may be easily seen, 

 though it has never been figured. 



The present specimen was snipped from the glans penis, a 

 favorite and undisturbed lurking-place. It consists of a canal 

 bored obliquely through the tissues, containing a series of twelve 

 eggs, together with fcecal matter, strewn along the passage. 

 When first cut out, the animal herself was seen at the lower ex- 

 tremity with one egg in her body. The first two or three 

 eggs were quite mature, so that the extremities of the young 

 could be distinctly made out. She generates but one egg a day, 

 though Bourgignon says he has seen four at once in her body. 

 Hebra thinks this impossible, and he is probably correct, as he 

 has made them an especial study, cultivating a colony on himself 

 for two or three months. He once saw the two sexes in act of 

 coition, belly to belly. The same species occurs on the lion, 

 camel, and other animals. 



Dr. White showed also the spores of the parasitic 

 plant of Pityriasis versicolor. 



The specimen was taken two or three days since from the 

 back of a gentleman who was not aware of any cutaneous dis- 

 ease. There were some dozen patches, the largest the size of a 

 pea. They present a yellow appearance, are elevated, and con- 

 sist of epidermal cells, between the layers of which the parasite 

 is found. Some alkaline carbonate is added to make the epi- 

 thelium transparent. It is still a mooted point whether the para- 

 site is the cause of the disease, or merely a growth in an exuda- 

 tive process. The fact that we sometimes fail to find the parasite 

 tends to the latter conclusion. Microscopically, it consists of 



