436 BULLETIN 120, UNITED STATES NATIONAL MUSEUM, 



into the tadpoles. Here the cysts hatch out and the little Opalinas 

 rapidly develop into multinucleated individuals of normal size. 



Shipley and McBride (1901) make brief reference to Opalinidae. 

 Their statements in regard to division are inaccurate : " When divi- 

 sion commences it continues until the resulting pieces have only one 

 nucleus each; they then grow and do not divide again until they 

 acquire the size they had before division took place and also the 

 same number of nuclei." 



Sand (1901-1902). This paper is not obtainable in this country. 

 A brief reference to it suggests tliat it may discuss in part the re- 

 actions of Opalinids to certain poisons. 



Enriquez (1902) regards the phenomena of ingress of food and 

 egress of water in Opalina ranarurri as physiological and not purely 

 osmotic. 



Zahn (1902) reports experiments upon Opalina ranarum^ using 

 1 per cent solutions of various poisons in spring water, observing 

 form, vacuolization and locomotion, after 5, 15, 25 and 35 minutes. 

 The Opalinas were completely destroyed by Fluornatrium after 35 

 minutes, by Hydroxylamin after 25 minutes, by Formaldehyd after 

 5 minutes. Three nerve poisons caused only functional disturbance. 

 With Curari, 0.001 per cent solution after 4 hours, " vollKtandige 

 Lahmung herbeif iihrte." Conclusion : The substances named above, 

 and also strychnine and morphine, are protoplasmic poisons, though 

 cessation of motion and ultimate death in an Infusorian after treat- 

 ment with chemical substances may be due not to direct protoplasmic 

 poisoning, but to interference with its functions, leading to degen- 

 eration. 



Keble and Gamble (1903) refers to the results of Cont<? and 

 Vaney (1902). 



Hickson (1903). The reference to Hickson's statements in my 

 previous review of the literature (Metcalf, 1909) was confused. Be- 

 ginning with the last sentence on page 140 it should have read, quot- 

 ing from Hickson : " The mitotic figures described hy Pfitzner are 

 clearly seen in a large number of sections examined, but they are 

 smaller than the meganuclei [no] and are probably formed by micro- 

 nuclei which, as in other forms, increase considerably in size before 

 division." [Each nucleus of Opalina seems to be functionally com- 

 parable to both micro- and macronucleus of higher Ciliata, but to be 

 homologous with each, both the nuclei of Ciliata being, both phylo- 

 genitically and ontogenetically, complete nuclei.] 



Kofoid (1903) places ^'■Opalina'''' with Profophnja^ Anoplophrya^ 

 Hoplitophrya, Discophrya, and Opalinopsis^ in the family Opa- 

 linidae, giving as diagnostic description of ''''Opalina'^'' [which in- 

 cluded, of course, the four present genera] " body flattened [not in 



