January — February iSSS.] 



PSYCHE. 



sites of this disease, an unusual number 

 of conflicting views have been lield by 

 successive \vriters. Levdig was the first 

 to suggest their affinity with the psoro- 

 sperms of fishes in 1857, ^'^'t they were 

 afterv^'ards claimed by botanists and de- 

 scribed, once as an alga (^Panhistophy- 

 ton ovatict7i) . by Lebert, and again by 

 Naegeli, as one of the Schizomycetes 

 or bacteria (^JVosema bombycis) . Even 

 in so recent and authoritative a work as 

 that by Cornil and Babes, Les bacie- 

 ries^ ct letir rdle dans Fanatomie et 

 Vhistologie patJiologiques des mala- 

 dies infect lenses^ published in 1S85, 

 this view of Naegeli is taken, and the 

 spores are classed as bacteria. But, 

 since the thorough-going researches of 

 Balbiani on their life-history, continued 

 from 1867 to 1883, I think that there 

 can be no longer a reasonable doubt of 

 their animal nature, or of their agree- 

 ment in general characters with those 

 forms now commonly included under 

 the head oi sporozoa., — a parasitic sub- 

 division of the protozoa, of which Gre- 

 garina is perhaps the best known type. 



The fullest and most satisfactory 

 account of their very simple life-history 

 is that given by Balbiani three years 

 ago, in his discussion of the Micro- 

 sporidia in the yournal de microgra- 

 phie (1883, V. 7, p. 313-323, and p. 

 404-411). It may be thus briefly sum- 

 marized : — 



The minute oval spores, colorless, 

 highly refractile, homogeneous in ap- 

 pearance, 4 ^ long by 2 |j. wide, when 

 swallowed with the food, penetrate in 

 some way unexplained the cuticle of 



the alimentary canal, and. in the cells 

 of its epithelium, open at one end and 

 emit their contents, each in a form of 

 an amoeboid speck of protoplasm. 

 This grows to a spherical bodv and, 

 by a process of internal segmentation 

 common to the sporozoa, is soon con- 

 verted into a mass of spores, each like 

 the original. These spores every- 

 where undergo a like development, and 

 load all the tissues with their products, 

 slowly and gradually arresting all the 

 functions of life. Their vitality is tem- 

 porary — Pasteur's experiments showing 

 that they will not germinate five weeks 

 after drying out — and the disease is 

 consequently maintained only by virtue 

 of its hereditary character. 



This microsporidion, or an extremely 

 similiar one, produces an epizootic dis- 

 ease also in the oak silk-worm {Atta- 

 cks pernyi) , in France, in that species, 

 however, being unable to penetrate 

 beyond the epithelial layerof the intes- 

 tine, and hence not appearing in the 

 blood or in the tissues at large. Other 

 forms of microsporidia have been found 

 in Coccus hesperidum ; in Tipiila 

 pratensis ; in Zygaena filipendula; 

 in two orthopterous insects {Decticus 

 griseus and Gry litis cajnpestris) ; in 

 E?nus olens^ a coleopterous species ; 

 in the arachnid Epeira diadema ; in 

 the entomostraca, Polypheinus pedicti- 

 lus, Siviocephahis vetiilus and Chy- 

 dorus sphaericus ; in the genital tubes 

 of a nematoid worm ; and even, accord- 

 ing to Vlacovich, in a colubrine snake 

 ( Coluber carbonarius). 



That epizootic attacks are not more 



