OF ARTS AND SCIENCES. 329 



Ml'. Chirk was appointed Adjunct Professor of Zoology at Harvard 

 College in the year 1860, which post he subsequently resigned in con- 

 sequence of a disagreement which arose between himself and Professor 

 Agassiz with reference to the work he had been doing under his direc- 

 tion. Plis own views of this unfortunate controversy have been pub- 

 lished in a pamphlet entitled "A Claim for Scientific Property." 

 During his residence at Cambridge, various communications from him 

 were read before this Academy, and the Boston Society of Natural 

 History, upon the microscopical structure of plants and of the lower 

 animals. He was j^articularly engaged at this time in researches upon 

 the structure and physiology of Lucernaria. The earlier results of 

 the investigation were given to the Boston Society of Natural History, 

 in March, 1862, in a paper entitled " Lucernaria the Ccenotype of the 

 Acalepha3;" but the Prodromus published in January, 1863, contained 

 only a brief statement of the work, and the materials afterward 

 swelled to such dimensions that it became impossible for the Society 

 to publish it. The Smithsonian Institution finally undertook the task ; 

 and the monograph, not yet published, will fill about four hundred 

 pages quarto, and will be illustrated by forty plates.* 



In January, 1864, Professor Clark announced the discovery of the 

 eggs of Tul)ularia. This group had previously puzzled observers, by 

 presenting the anomaly of a female form producing young by a system 

 of budding and destitute of true ova, though the male elaborated sjDer- 

 matozoa. This discovery led Professor Clark to the very important 

 conclusion that " there was but one type of development in the Me- 

 dusoids of all the Hydroids," — an exceedingly valuable addition to 

 our knowledge of the affinities of the various groups of Medusae. 

 During the course of these observations, he was attracted to the 

 study of still lower forms; and we find him in September, 1863, pub- 

 lishing an important contribution, in which he demonstrated the cellular 

 structure of Actino2:)hrys, Difilugia, and other forms, and finally in 

 December, 1865, comparing the structure of the Cilio-flagellati Infu- 

 soria with that of true sponges, and announcing his opinion that Leuco- 

 solenia, a form of calcareous sponge common on this coast, was really 

 a compound mass of monads, allied to Codosiga. In this conclusion 

 he has been supported by the observations of Carter, antf^t opposed in 

 common with Carter by Hjeckel in his late work upon calcareous 

 sponges. 



* See Prod, of the Hist., Struct., and Physiol, of the order of Lucernaria. 

 Boston Jour. Nat. Hist., vol. vii. p. 531. 

 VOL. I. 42 



