BEVIEW — TEOPICAL MEDICINE, ETC. 181 



human vaccine lymph be gathered on the eighth or ninth day of the eruption in a capUlary tube and subsequently Small-pox 



centfifugalised — if the centrifugilate be examined as a hanging-drop, certain cellular elements very Uke continued 



leucocytes will be seen ; if the preparation be kept for seventy-two hours longer the cellular elements will have 

 disappeared. It can therefore be affirmed that in human vaccine lymph the bodies which are assumed to be 

 leucocytes disappear in a comparatively short space of time. Furthermore, the parasites in the forms of spores, 

 encysted parasites, and morulee have no morphological resemblance whatever to either leucocyte, lymphocyte, or 

 epithelial cell. 



In the same article he points out that the evidence is so far against a bacterial cause for 

 small-pos and vaccinia, and suggests that in small-pox the secondary fever is due to the 

 pyogenic organisms which gain access to the pock about the seventh or eighth day. 

 Moreover, he refers to the fact of the complete absence of infectivity during the incubation 

 period of the disease, and, as additional evidence of the nidus of the virus being the skin 

 (in which it is imprisoned during the incubation period), cites a case where variola was 

 conveyed during the incubation period, to a second individual, by means of skin grafts. 



He alludes to the organisms described by Guarineri and certain American observers, 

 stating that it is impossible to say whether these are different from those described by Funk 

 and himself or whether they represent another stage in the life-history of the same organism. 

 He and Funk deal with the contents of a lesion which is practically extra-corporeal, the 

 others with an intra- corporeal lesion. 



One cannot deal at length with the parasite of Guarnieri, Gytoryctes variolse, which has 

 been worked at by Calkins, Councilman, Bancroft and others. The technique required for its 

 demonstration is more complicated necessitating the preparation of skin sections. 

 Councilman^* states : — 



It is believed that the organism which constitutes the virus of vaccinia and smaU-pox is the same : that 

 in vaccinia it undergoes a definite cycle of development, resulting in a structure, the gemmules arising from 

 simple growth and segmentation ; that in small-pox a further and more complicated cycle of development, 

 in which probable sexual forms occur, is added to the vaccine cycle. It is only in man and in the monkey 

 that the conditions are favourable to the development of the cycle which constitutes small-pox. The intranuclear 

 parasites are as characteristic for small-pox as are the cytoplasmic forms for vaccinia. They are found in both 

 variola inoculata and in variola vera. The spores which arise from the multiplication of the intranuclear 

 bodies constitute the contagion of small-pox, which is capable of air transmission. This introduced into a 

 susceptible animal develops the typic disease, small-pox, both cycles of the organism taking place in the lesions. 

 In the non-susceptible animal, such as the calf or rabbit, only the single, and probably a sexual, cycle is 

 developed constituting vaccine. 



Eeference may also be made to a long extract in the Medical Anmial for 1907. 

 Davies'^ epitomises the subject as follows : — ■ 



In every sporozoon definite reproductive phases occur, characteristic of some phase of disease, or of some 

 peculiar enviromnent of the parasite, as, e.g. in the malarial parasite. 



Stage A. — Asexual reproduction or schizogony (takes place in the blood corpuscle of man or bird). 



Stage B. — Sexual cycle or sporogony (takes place in the digestive tract of the mosquito). 



Apparently, from Calkin's observations, an analogous series of processes takes place in the parasite causing 

 vaccinia and variola ; cytoryctes variola, with this important variation : — 



Stage A. — Asexual phase or schizogony (vaccine body) (takes place within the cells of the rete mucosum 

 outside the nucleus). 



Stage B. — Sexual cycle (takes place within the nuclei of these cells). 



Thus the complete cycle of multiplication and of sexual reproduction is perfected in one host. 



(«) The first development of the germ in the host is unknown ; probably a multiplicative reproduction 

 occurs, as a result of which gemmules are carried by the blood to the skin, where the further development 

 takes place ; so much is conjectural. From this point observations are fairly complete. 



(6) The gemmules become intracellular (cytoplasmic) amoeboid organisms, which give rise to similar 

 gemmules (Councilman's vaccine cycle). This process must continue for some time, as the gemmules are, in 

 variola, distributed to all regions of the skin. 



(c) Ultimately the germs derived in this way give rise to forms which penetrate the nuclear membrane 

 and develop into gametocytes of two types, male and female. Conjugation probably follows, zygotes develop 

 into a large amoeboid organism in which pansporoblasts originate, which give rise to primary sporoblasts, and 

 these to multitudinous spores; all this propagative reproduction takes place within the nucleus. 



{d) The infection of fresh nuclei ; and 



(e) The transmission to new hosts, may be readily grasped. 



An important point is that evidence of every stage in the first (cytoplasmic cycle) indicates that in 

 vaccinia and v.ariola we have to do with the same organism which in vaccinia has undergone some modification 

 by reason of which the nuclear phase is inhibited. 



' Councilman, W. T. (October 21st, 1905). American Medicine. 



' Davies, D. S. (March, 1907), " Diphtheria and SmaU-pox : an Epidemiological Contrast." Putlic Health, 

 Vol. XIX. 



• Article not consulted in the original. 



