298 



SCIENCE. 



[N.S. Vol. XXIV. No. 610. 



like other nematoeerous diptera studied, the 

 eyes— both dorsal and lateral— are of the 

 pseudocone type. Among the numerous 

 slender secondary pigment cells may occa- 

 sionally be found a much-reduced trichogen 

 cell. There is no special corneal hypo- 

 dermis such as is present in Crustacea and 

 Collembola, but it is represented by the pri- 

 mary pigment cells. The presence of abun- 

 dant pigment between the ommatidia and 

 the position of the visual rods preclude the 

 formation of superimposed images. There 

 is no evidence of pigment migration de- 

 pendent upon intensity of light. In the 

 youngest pupse studied the eye is repre- 

 sented by a one-layered hypodermis in 

 which groups of enlarged sensory cells are 

 separated by more slender cells. There is 

 no invagination, but the groups of sensory 

 cells become bud-like, pushing the pseudo- 

 cone cells and the primary pigment cells to 

 their distal surfaces while the secondary 

 pigment cells become crowded into wedge- 

 shaped masses at either end. In course of 

 further growth the elements elongate great- 

 ly. The lateral eye differentiates more 

 rapidly than the dorsal, a condition to be 

 explained by the late phylogenetic appear- 

 ance of the dorsal eye. 



The Nervous System and Nephridia of 

 Dinophilus: J. A. Nelson, Cornell Uni- 

 versity. 



The nervous system exhibits an embry- 

 onic condition, consisting of a brain in close 

 contact with the hypodermis, and a pair of 

 lateral nerve cords, connected by trans- 

 verse commissures arranged metamerically. 

 Ganglion cells, lying within the hypo- 

 dermis, accompany the lateral nerve cords, 

 and are arranged to form five pairs of 

 ganglia. A preoral commissure connects 

 the circumoesophageal commissures. The 

 nephridia number five pairs, and are ar- 

 ranged metamerically. Those of the pos- 

 terior four pairs are simple, and similar to 



those of annelid larvaj, terminating blintlly 

 at their inner ends. Those of the first pair 

 are much more complex, each exhibiting 

 two curious canalar plexuses. The whole 

 anatomy indicates close relationship to the 

 annelids. 



Early Stages in the Development of the 

 Salivary Glands in Sheep and Pig Em- 

 bryos: Wm. C. Theo, Cornell University. 

 Glands in Sheep Em'bryos. — In an em- 

 bryo 17.5 mm. long all the glands are pres- 

 ent. The submaxillary is the most ad- 

 vanced, since a few side buds project from 

 the body of the gland. The sublingual 

 consists of a short ridge-like projection of 

 the epithelium lining the mouth-cavity. In 

 a 20 mm. embryo the sublingual consists of 

 a solid cord of cells attached by its cephalic 

 end to the epithelium lining the mouth- 

 cavity and running caudad a short distance 

 beneath the epithelium. In a 26 mm. em- 

 bryo Wharton's duct possesses a lumen. 

 In a 43 mm. embryo the sublingual and 

 parotid have lumina. In an embryo 44.5 

 mm. long the ducts of the submaxillary 

 and sublingual run side by side and open 

 beneath the tip of the tongue, cephalad of 

 the frenum. 



Glands in Pig Emhryos.— In an embryo 

 15 mm. long, head-breech measurement, the 

 very earliest stages of the parotid and 

 retrolingual glands are found, while the 

 submaxillary is represented by a well-de- 

 veloped bud with enlarged extremity. 



The Development and Relations of the 

 Columella in the Amphihia: B. P. Kings- 

 bury, Cornell University. 



The Inheritance of Characteristics in 

 Poidtry: C. B. Davenport, Carnegie 

 Institution of Washington. 

 In how far are the characteristics of or- 

 ganisms immutable units, incapable of 

 modification, even when pitted against 

 each other in pairs, as occurs in hybridiza- 



