ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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ascertain if these be of parasitic origin. Actinomycosis may be safely 
quoted as an instance of parasitic disease, while a similar origin for 
other tumours, such as melanosis in horses, may be more than suspected. 
After alluding to the transmissibility of actinomycosis from man to 
animals and vice versa , the method of infection, the immunity of Car- 
nivora, the author turns to other tumours, the existence of which 
depends on the immigration of micro-organisms. 
Botryomyces and Discomyces, two fungi closely allied to Actinomyces , 
are found in those large fungous tumours which frequently develope in 
horses after gelding. In the numerous small abscesses which appear in 
the new growth are found bright points resembling the grains of 
Actinomyces , only somewhat smaller. 
To melanosis, a common disease of horses, the author attributes a 
parasitic origin, the black granules besetting the tumour probably con- 
taining the parasite, which is, perhaps, a protozoon. Cultivations made 
with the granules have, however, hitherto failed. A parasitic origin is 
also claimed by Dominic for the papillomata of oxen (. Bacterium porri ), 
by Czokor for Epithelioma contagiosum of birds (a Gregarinid), and by 
Perroncito for the cyst-formations on the mesentery and pleura of birds 
(. Aspergillus nigrescens ). 
Frequently too the tumours of plants have a parasitic origin ; such 
tumours may be induced by infusoria (on the roots of Leguminosse), by 
bacteria (tumours on fir and olive trees), and by higher fungi (the 
tumours on maize). The Blasmodiophora hrassicse , the cause of the 
tumours on cabbages, may belong to the group of Actinomyces fungi. 
Although the parasitic theory of tumour formation is very seductive, 
the author cautions against general conclusions, on the ground that the 
vast majority of inoculation and transplantation experiments have been 
negative. The ill success of these experiments is declared by the author 
to be due to the neglect of certain important factors influencing tumour 
formation, in the choice of the inoculated animals. For example, no 
account is taken of age, an important factor in tumour formation, nor of 
the kind of animal to be inoculated, those usually operated on being 
rabbits and guinea-pigs, animals little prone to be affected by tumours ; 
nor of the tissue to be selected for the experiment, that usually chosen 
being the subcutaneous tissue, a part in which tumours rarely develope 
spontaneously. Better results would possibly be obtained by attending 
to such conditions. 
Osteomyelitis and Streptococci.* — MM. Lannelongue and Achard 
find from experiments that pyogenic Streptococci can produce in bone- 
marrow changes similar to those brought about by Staphylococci. The 
osteomyelitis induced by Streptococci is rarer than that caused by 
Staphylococci. 
Microbes of Acute Infectious Osteomyelitis.f — MM. Courmont and 
Jaboulay find from intravenous injection of rabbits that suppuration of 
bone can be induced by several kinds of micro-organisms. The osseous 
* CR. Soc. Biologie, 1890, No. 19. See Centralbl. f. Bakteriol. u. Paraeitenk 
viii. (1890) p. 731. 
t GR. Soc. Biologie, 1890, No. 18. See Centralbl. f. Bakteriol. u. Parasitenk 
viii. (1890) p. 731. 
R 2 
