MEDICAL MICROSCOPICAL SOCIETY. 103 



body, and two well-formed monads are set free. These swim 

 freely until they attach themselves to an ordinary form that has 

 just eoiupleted fission, so that the nuclei are approximate. Sar- 

 code and nuclei melt into each other ; the form becomes free, 

 swimming and irregular in shape — rests — loses its flagella ; be- 

 comes clear and distended ; then bursts at the angles, pouring out 

 indescribably minute granules from which myriads of new forms 

 arise and repeat the cycle. 



Mr. Alfred Sanders read a paper " On the Art of Photo- 

 graphing Microscopic Objects," in which he showed that the 

 costly apparatus and elaborate arrangements frequently regarded 

 as essential to success might readily be dispensed with, and the 

 most satisfactory results obtained with appliances of the simplest 

 kind. 



Mr. S. J'. M'Intire read a paper entitled "Notes on Acarellus," 

 in which he described certain insects found parasitic upon Obisium, 

 and closely resembling the Hyopus of the Micrographic Dic- 

 tionary, and the insect mounted by Mr. Topping under the name 

 of " Parasite of House-fly." The paper was illustrated by draw- 

 ings and specimens, both alone and mounted. 



Medical Miceoscopical Society. 



The following is an abstract of Mr. Hogg's paper read at a 

 previous meeting of the Society on " the Pathological Relations of 

 the Diphtheritic Membrane and the Croupous Cast." 



Much misapjirehension rests on this subject ; some practi- 

 tioners decide at once on what they believe to be the character of 

 the membrane. Other authorities, as, for instance Sir T. Watson, 

 give in their adhesion to the unity of all membranous affections. 

 Although the epidemic of diphtheria in 1858 and 1859 attracted 

 much attention to the subject, and many specimens were exhibited 

 by members of the Pathological Society of Loudon, very conflict- 

 ing statements were made about their histological character. In 

 the author's opinion, the diseases are very different. " While one 

 disease, diphtheria, is most decidedly epidemic and endemic, often 

 wide-spreading and affecting a large proportion of adults, and 

 probably belonging to a specific form of fever ; the other, croup, 

 is essentially sporadic, often a local aftection, not communicable, 

 or only so in a small degree, as when a family predisposition 

 exists, mostly occurring in childhood, and rarely after it is fairly 

 passed." Histologically, also, he maintains that a sharp line can be 

 drawn between the diphtheritic membrane and the croupous cast. 



As to the naked-eye appearances, the diphtheritic membrane is 

 a dense compact, opaque, yellowish- white or reddish-grey coloured 



