90 



SCIENCE 



[N. 8. Vol. XXXVI. No. 916 



this reason were given. It will be interesting 

 to note the manner in which Mr. Nash in the 

 future parts of the work solves the various 

 difficulties which will beset him in fixing the 

 types of the genera. 



The name Tripsacum acutiflorum Fourn. 

 (Bull. Sec. Bot. Belg. 15: 466. 1876) is ac- 

 cepted in place of T. lanceolatum Kupr. 

 (Fourn. Mex. PI. 2: 68. 1881). This is based 

 upon the statement made by Fournier, in a 

 discussion of grasses with separated sexes, that 

 in Tripsacum the peduncle of the male spike- 

 let, ordinarily free, " est sonde avec le raehis 

 de I'epi dans le T. acutiflorum n. sp." This 

 statement certainly does not distinguish T. 

 lanceolatum from the other species and can 

 scarcely, therefore, be considered as sufficient 

 to constitute publication. It is rather to be 

 taken as incidental mention within the mean- 

 ing of the American Code of Botanical Nom- 

 enclature (Canon 12. A name is not pub- 

 lished by its citation in synonymy, or by inci- 

 dental mention). The allies of Botthosllia 

 cylindrica have difficulty in keeping their 

 names. When Otto Kuntze showed that the 

 type species of Manisuris was a Eoithcellia, 

 the names of these species were changed from 

 Bottlcellia to Manisuris. Now Mr. Nash de- 

 cides that this group is not congeneric with 

 the type of Manisuris, but belongs to the 

 genus ' Stegosia and the species are all trans- 

 ferred to the new allegiance. At the same 

 time that Kuntze made the disconcerting dis- 

 covery mentioned above he found it necessary 

 to change the name of the grass generally 

 called Manisuris granularis, since it obviously 

 was not a true Manisuris. He called it HacJc- 

 elochloa granularis, and is followed in this by 

 Mr. Nash (and also by the present writer. 

 See " Grasses of Cuba ")• However, it ap- 

 pears necessary to take up for this genus the 

 name Eytilix Eaf . (Bull. Bot. Seringe, 1 : 219. 

 1830). 



While Mr. Nash's contribution is not, and 

 could not be expected to be, monographic, it 

 will be, when completed, of great service to 

 agrostologists. 



A. S. Hitchcock 



SPECIAL ARTICLES 



RHYTHMICAL ACTIVITY OF ISOLATED HEART 



MUSCLE CELLS IN VITRO 



In previous communications'^'^ I pointed 

 out that the heart muscle of chick embryos 

 will beat rhythmically for many days when 

 suspended in the media of a tissue culture 

 and from such transplanted tissue there is an 

 active growth of cells into the surrounding 

 media. Braus^ has repeated these experi- 

 ments, using the hearts of embryo frogs and 

 toads and he has found that these isolated 

 beating hearts react to electrical and chem- 

 ical stimuli similar to the intact heart. 

 Braus also noted that the cells which grew 

 from the hearts of cold-blooded animals were 

 living at the end of three months. Very 

 recently. Carrel* by the use of the method of 

 repeated transplantation of the tissue from a 

 culture to a fresh medium (Carrel and Bur- 

 rows) has attempted to prolong the life and 

 function of heart muscle in vitro. His ex- 

 periments show that the rhythm which I 

 noted in fragments of embryonic chick hearts 

 can be prolonged, although intermittently, 

 for a period of 85 days. The results of these 

 experiments substantiate, therefore, the former 

 well-known fact, namely, that strips of heart 

 muscle, both of cold and warm blooded ani- 

 mals (Erlanger), will beat for some time when 

 placed in the proper media. In none of these 

 cases could one rule out, however, the possi- 

 bility of the existence of nerve ganglia or 

 some possible precursor in the young embry- 

 onic hearts, which might initiate rhythmical 

 contractions. 



During the present year experiments have 

 been made to determine the conditions which 

 would prolong the life and allow the develop- 

 ment of functional activity in the cells which 

 had grown and differentiated in the culture. 



* Burrows, M. T., 1911, Jour. Exp. Zool, Vol. 

 10, 63. 



= Burrows, M. T., 1912, Anat. Becord, Vol. 6, 

 141. 



° Braus, H., 1912, Weiner Med. WocJischr., No. 

 44. 



•Carrel, A., 1912, Jowr. Exp. Med., Vol. XV., 

 516. 



