March 20, 1914] 



SCIENCE 



437 



the site of the closing blastopore. (2) During 

 gaatrulation there is a ooufluenee of material lying 

 in the region of the dorsal lip of the blastopore; 

 in connection with the process of overgrowth and 

 in turning of the dorsal lip of the blastopore this 

 material shifts from either side toward the median 

 line. (3) The movement of the neural folds is a 

 movement of translation, not a wave movement. 

 The neural folds include material originally situ- 

 ated at least 90 degrees apart, which is thus 

 brought into apposition in the median line. 



The bearing of these facts on the theory of 

 concrescence will be discussed when the paper is 

 published in full. 

 The Behavior of the STceletons in Experimentally 



Fused Larvce: A. J. Goldpabb. 

 On the Behavior of Sea-urchin Embryos When In- 

 corporated in Sea-urchin Lymph Plasmodia: H. 



V. Wilson. 



Segmenting eggs included in lymph Plasmodia, 

 eventually in wound membranes, continued to de- 

 velop for a time. Many reached through radial 

 elongation of the blastula cells and subsequent de- 

 lamination a solid (sterroblastula) stage, after 

 which the cells became dissociated, lying scattered 

 or in amorphous masses in the midst of the gen- 

 eral Plasmodium. A large amount of the embry- 

 onic tissue underwent degeneration. On the other 

 hand, groups of small dissociated blastomere cells 

 established connection with one another and the 

 general lymph Plasmodium through the develop- 

 ment of protoplasmic processes. They thus went 

 so far as to become a part of the syncytium which 

 constitutes the regenerative tissue. Their further 

 fate could not be traced, and the evidence as to 

 their permanency is thus negative. 



In some of the experiments a considerable num- 

 ber of segmenting eggs remained adherent to the 

 surface of the Plasmodium. The development of 

 these was near the normal. About the time when 

 the cells acquire cilia, instances of fusion between 

 the blastulse were common. While the further de- 

 velopment of these giant blastulae was not followed, 

 it would seem that the combination of lymph Plas- 

 modium and giant embryos is something essentially 

 like the " syrphoplasmic " masses described by 

 Janssens (1904). 

 A Pair of Tracheal Invaginations on the Second 



Mamillary Segment of the Embryo of the Honey 



Bee: J. A. Nelson. 



At a i)eriod shortly after the completion of the 

 germ layers, and contemporaneous with the ap- 

 pearance of the rudiments of the appendages and 



of the stomodasum, a pair of tracheal invaginations 

 appears on each of the ten segments caudad of 

 (but not including) the prothoracie segment. 

 These invaginations by branching give rise to the 

 tracheal system. At the same time a pair of in- 

 vaginations appears on each side of the second 

 maxillary segment. These occupy a position on 

 this segment similar to those of the tracheal invag- 

 inations of the trunk segments, and are also similar 

 to them in size and general appearance. Each of 

 the tracheal invaginations of the second maxillary 

 segment is directed somewhat caudad, and develops 

 with great rapidity into a sac with four diverticula 

 and a constricted external opening. One of the di- 

 verticula is directed caudad, one dorsal and the 

 other two cephalad. 



The external opening of the tracheal invagina- 

 tion now closes completely, the branched sac thus 

 formed being cut off completely from the hypo- 

 dermis. The caudad diverticulum of the sac now 

 extends further caudad to meet and unite with the 

 cephalad diverticulum from the tracheal invagina- 

 tion of the second thoracic segment. The dorsal 

 diverticulum extends toward the dorsal mid line, 

 where it meets and fuses with the corresponding 

 diverticulum of the opposite side, forming the an- 

 terior tracheal loop or commissure of the main 

 tracheal trunks. The two cephalad diverticula 

 form tracheal branches supplying the brain and 

 the muscles of the cephalic appendages. The 

 tracheal invaginations on the second maxillary seg- 

 ment, therefore, produce a portion of the anterior 

 end of each of the main tracheal trunks, in addi- 

 tion to the tracheae found in the head. 



Tracheal invaginations were described by Hat- 

 schek in 1877 in the gnathal segments of a lepidop- 

 terous larva. Examination of Hatschek's figures 

 show that these invaginations were those forming 

 the tentorium and mandibular apodemes, and they 

 have generally been so regarded. Tracheal invagi- 

 nations have not since been described in the head 

 of any insect embryo. 



Further Studies on the Development of the Cranial 

 Sympathetic Ganglia in Vertebrates: Albert 



KUNTZ. 



The Early Cleavage of Cirratulus Grandis, Verrill: 

 John W. Scott. (Illustrated with lantern 

 slides.) 



In common with most annelids the cleavage is 

 unequal. It differs from other marine annelids in 

 that cleavage becomes very irregular after the 8- 

 celled stage. The egg is further characterized by 

 the peculiar and important behavior of the yolk 



