ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 221 



tlio necessary carbon ; tliis carbon may bo utilized solely by the 

 cblorophyll-corpuscles tbemselves. 



M. Girocl agrees witli tbosc zoologists wlio describe a membrane 

 aronnd tbe cbromatopbores of tbe Cepbalopoda, and be assigns to its 

 elasticity tbe function of reducing tbe extent of tbese structures ; be 

 gives a full account of tbe structure and development of tbe ink- 

 gland, and sbows tbat its secretion must be ranged witb cuticular 

 formations ; be bas not been able to find copper in tbe ink, altbougb 

 it is present in tbe blood, but tbere is iron, as in mammalian pig- 

 ments ; tbe "ink" is notbing more tban sligbtly modified bsemo- 

 cyanin ; be doubts wbetber tbese pigments are derived from tbe 

 colouring matter of tbe blood. 



Physiological Action of the Salts of LitMum, Potassium, and 

 Rubidium.* — M. C. Eicbet bas experimented witb tbe cblorides 

 of litbium, potassium, and rubidium on various animals. A weak 

 dose kills crayfisbes, because an injection is always intra-venous and 

 not only subcutaneous ; tbe large doses required to kill a slug are 

 explained as due to tbe extreme vitality of tbe tissues ; for most 

 animals, bowever, tbe toxic dose is mucb tbe same, and tbe mean is 

 for litbium O'lO, for potasb 0*50, and for rubidium I'OO; tbia 

 relation tbe autbor regards as pretty mucb tbe same as tbe atomic 

 weigbts of tbese tbree metals, 7, 39, and 85. By dividing tbe 

 numbers obtained in bis experiments by tbe atomic weigbts be gets 

 a mean of 0'0128, and be proposes tbe following formula. If P be 

 tbe atomic weigbt of an alkaline metal, tbe quantity necessary to kill 

 an animal weigbing one kilogramme will be P X 0*0128. It is 

 concluded tbat tbe toxic is identical witb a chemical action, and tbat 

 a molecule of tbe salt is necessary to poison the same weigbt of a 

 living animal. 



Tactile Organs of Insects and Crustacea.! — The Grand Prix 

 des Sciences Physiques has been awarded to Dr. J. Chatin for his 

 essay on the Tactile Organs of Insecta and Crustacea ; be bas ex- 

 amined all the parts of the mouth-organs, and has compared their 

 homologous regions; the antennae have likewise been investigated, 

 and tbe structure of tbe nerve-filaments and the constitution of tbe 

 subcutaneous plexus is described. The percipient hairs have been 

 studied, and the function of the so-called soft cones is reconsidered. 



Mollusca. 



Development of Genital Organs of Hermaphrodite Gastropoda. | 



— M. H. Kouzaud lias studied tbe development of the genital organs 

 of some hermaphrodite Gastropods ; he finds that, in the Pulmonata 

 however complex its constitution may be in the adult, the apparatus 

 always arises from a homogeneous and massive cellular bud, which 

 may be called the primitive bud ; it ordinarily appears just before the 



* Comptes Rendua, ci. (1885) pp. 707-10. f Ibid., pp. 13G8-71. 



X 'Reclierchea sur le developpement des organes ge'nitaux de quelquea 

 Gaste'ropodea hermaphrodites,' 8vo, Paris, 1885. Cf. Rev. Sei. Nat., iv. (1885) 

 pp 517-24. 



