1921] NATURAL SCIENCES OF PHILADELPHIA. 165 



enemy. To these successive explosions we must attribute the char- 

 acteristic leaps in Trentonia.^^ 



I must mention, before concluding, the existence of gelatinous 

 cysts, which I found numerous at Pinchat, in the month of May. 

 They are very similar to those of Cryptomonas ovata, and contain 

 either one single individual, or very often two, longitudinally applied 

 to each other, undoubtedly a result of division. Sometimes, in- 

 stead of two individuals, four are found, or two couples, one to the 

 right and the other to the left inside the gelatinous cyst, which 

 w^ould certainly indicate a second division. 



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^' When discussing Cryptomonas ovata, we had recourse to the trichocyst 

 theory for explaining the sudden backward jumps, and the facts here obtained 

 may be of considerable value as indicating greater probability in the former 

 suggestion. 



