308 Hemar'ks on the Impregnation of Plants. 



Fig. 4. Mouth apparatus — aba' upper limits of lower lip — cc' the extremities 

 of the transverse bony arch — de, bone which curves at e and passes towards the 

 base of the maxilla — f, F maxillae, the lower extremities of which are beneath the 

 lower lip. 



Pig. 5. g, g' internal bones connected with the maxillae f,f' and situated in the 

 animal as here represented. 



Fig. 6. One of the jointed bony rays of the suction legs. 



Fig. 7. First pair of natatory legs, exhibiting the two terminating pinnulae, of 

 which one is jointed at its extremity, and also the recurved pinnula, jointed near 

 its middle — also the ridges of hairs which in the animal are represented near the 

 posterior margin of the legs. These hairs are perspectively foreshortened. 



Fig: 8. Particles observed in the circulating fluid. 



Fig. 9. Back view of the Argulus Catostomi, the right hand side exhibiting 

 the circulation, the left hand, the muscles which move the shell, and the organs 

 below as seen through the transparent parts above — i, i, the antennary current — 

 n, the return current of the same — h, the ophthalmic, (seen most distinctly below) — 

 k, k, k, and m, lateral current whose direction is pointed out by the arrows they 

 contain. The arrows in the tail mark the direction of its currents — z, z, the junc- 

 tion of the shell with the abdomen. On the left, i, o, k, m, represent four muscles 

 by which the animal moves its shell. Three of the blood vessels above pointed 

 out, i, k, m, are in the direction of these muscles — i,i, move the clypeus — o, a 

 ' portion of the shell between the clypeus and x — k, and m, the lateral and posterior 

 parts of the same. 



Fig. 10. Under view of the young of the Argulus Catosionii. 



Fig. 11. Termination of the legs corresponding to the suction legs in the per- 

 fect animal, the spine partly separated from its sheath. 



Art. XIX. — A Translation of a memoir entitled " Beitrage zur 

 Lehre von der Befruchtung der Planzen,'^ (Contributions to the 

 doctrine of the impregnation of plants;) by A. J. C. Corda: 

 published in the 17th volume of the Nova Acta Physico-medica 

 Academiae Caesar. Leopold. -Carol. Naturae Curiosorum. Breslau 

 and Bonn, 1835; — With prefatory remarks on the progress of 

 discovery relative to vegetable fecundation ; by Asa Gray, M. D. 



Read before the Lyceum of Natural History, New York, Oct. 24th, 1836. 



The last volume of the transactions of the Imperial Acad. Naturae 

 Curiosorum, just received through the kindness of the learned Nees 

 Von Esenbeck, the president of that society, contains a brief memoir 

 on the impregnation of plants, which will doubtless be read by the 

 botanist and the physiologist with more than ordinary interest. M. 

 Corda, in the paper referred to, gives an account of an original and 

 highly curious series of observations on the structure and develop- 

 ment of the ovules, and the mode in which impregnation is effected, 

 in the natural family Coniferae. The memoir is illustrated by nu- 

 merous admirably executed figures. 



