SPIROCHJETES IN TICK EGGS 81 



Hindle, and others. It has been shown that the 

 small coccoid bodies float at first in the vitellus. 

 The first organs that develop within the egg take the 

 form of two long narrow structures which are the 

 primitive Malpighian tubules. Each at first consists 

 of only a few cells, but into each of these the spiro- 

 chaetes penetrate. The ovoid bodies also concentrate 

 in the cells and form small clusters. The large 

 spirochaetes, once they have penetrated, rapidly 

 divide and produce spores. Hence the Malpighian 

 tubules soon become crowded with granules collected 

 in clusters. The same procedure is followed, whether 

 the eggs be those of Ornithodorus moubata, the carrier 

 of Spirochceta duttoni, or Argas persicus, that transmits 

 the parasite of fowl spirochsetosis. The results of 

 microscopical examinations of infected ticks' eggs 

 may now be shortly summarized : 



The egg, when freshly laid, shows as a rule no 

 spirochaetes. It is only in extremely thin smears of 

 the egg, and then with difficulty, that the tiny ovoid 

 bodies can be detected. When the eggs have been 

 incubated from three to five days, the Malpighian 

 tubes of the young embryo have developed. Some 

 of the yolk also has been absorbed, and consequently 

 it is much easier to detect the ovoid bodies which 

 have concentrated in groups in the developing 

 Malpighian tubes. Some of the spores also have 

 begun to lengthen. 



Six to seven days of incubation results in more 



organs of the tick having formed. The ovoid bodies 



have lengthened in many cases, and some of them 



have ruptured the cells in which they were lodged, 



6 



