476 



SCIENCE 



[N. S. Vol. XXXIX. No. 1004 



ventral epidermis, which are directed obliquely 

 posteriorly and mesially. In the structure of each 

 pit seven cells are involved. Six of these cells 

 form a sensory syncytial lining or wall of the 

 pit. These six cells are recognized by their 

 nuclei, three of which form a dorso-ventral 

 row in the lateral wall of the pit and three a 

 similar row in the mesial wall. Stout cilia are 

 borne by the general surface of the syncytial 

 wall. This suffices for the prevalent conception of 

 the structure of the ciliated pits of flatworms. 

 But all of the surface of the wall of the pit does 

 not bear cilia. Just over the middle nucleus of 

 each side there is a well-difiEerentiated sensory rod, 

 so that we may look upon the wall of the pit as 

 being formed by four accessory cells and two 

 sensory cells. A special nerve from the ganglion 

 runs to the posterior dorsal part of the sensory 

 cells of each pit. The seventh cell of the pit is a 

 large gland-cell, which crowns the widened base of 

 the pit. The contour of this gland-cell is quite 

 as indefinite as that of the unicellular glands of 

 the general epidermis. Its secretion granules, how- 

 ever, can be differentiated from the secretion 

 granules of the general epithelial glands by the 

 use of Bordeau red. This unicellular gland opens 

 by pores through the wall of the pit at the an- 

 terior angle of the fundus. 



Therefore, as we have shown in Microstoma 

 caudatum, the ciliated pit is not a simple highly 

 ciliated structure, but it is differentiated into a 

 ciliated, sensory region and a glandular region. 

 Thus the inferred affinity between the Flatyhel- 

 mintlies and the Nemertine is strengthened by the 

 close resemblance between the structure of the 

 ciliated pit of the former to that of the simpler 

 cerebral organs of the latter. 



The Experimental Modifications of Tiger Beetle 

 Color Patterns ly Variation of Temperature 

 and Moisture During Ontogeny: V. E. Shel- 

 roED. 



Some Experiments on Begeneration in Thinodrilus 



limosus: Mary T. Haeman. 



Both the anterior and posterior regeneration has 

 been considered. At the anterior end of any piece 

 the maximum number of segments regenerated is 

 six plus the prostomium. The first external indi- 

 cation of differentiation is the differentiation of 

 the prostomium followed closely by the first seg- 

 ment. After that the segment adjacent to the old 

 part of the worm is differentiated from the newly 

 regenerated portion and then the segments are 

 differentiated from the base toward the tip in reg- 



ular order. Although six segments plus the pros- 

 tomium are the maximum number of segments re- 

 generated, the size of the regenerated portion and 

 the rate of regeneration varies with the level of 

 the cut and is independent of the size of the re- 

 generating piece and the amount of injury. 



There is, also, a region of maximum rate of 

 posterior regeneration and this is independent of 

 the size of the regenerating piece and the degree 

 of injury. The amount of posterior regeneration 

 increases rather suddenly from the head to the re- 

 gion of maximum rate of regeneration and then 

 decreases more gradually toward the tail region. 

 Pieces taken from the most posterior part of the 

 worms do not live long and seldom show any re- 

 generation. The direction of differentiation in 

 the posterior regenerated part is from the base 

 outward. However, the anal opening is soon 

 formed. During regeneration a part of the most 

 posterior portion of the regenerated tail remains 

 unsegmented as a sort of segmental plate. 

 Will an Earthworm Begenerate Anterior Segments 



When the Enteric Epithelium is Absent From 



the Cut Surface? : H. W. Band and H. E. Hunt. 

 The Fly, (Estrus Ovis, Parasitic in Man: H. F. 



Peekins. 



More than a hundred living larvsB were dis- 

 charged from a lung abscess in pus and mucus by 

 a boy ill for several months. These small larvse 

 were identified as the early stage of the sheep bot 

 CEstrus ovis and this determination has been cor- 

 roborated by the Bureau of Entomology. Infec- 

 tion was by the mouth, the fly and the larvae seem- 

 ing to be attracted by the purulent discharges. 



No case seems to have been recorded of an in- 

 sect parasitic in the lung of man or any other 

 mammal, and CE. ovis, while it has been found in 

 the frontal sinuses and rarely in the eyes and 

 throat walls of man in Algeria, has only once or 

 twice been found in man in America. The species 

 is not uncommon in the region where this boy lives, 

 and he took care of sheep for three years previous 

 to his illness. 



The larvae were probably living in the abscess 

 for at least three months, but none of them devel- 

 oped beyond the third stage, whereas normally 

 they would in the same time have developed into 

 flattened grubs of ten times the bulk, this re- 

 tarded growth being attributable to the lack of 

 oxygen in the non-functional lung. 

 The Effect of Alcohol on the Male Germ Cells, 



Studied by Means of Double Matings: L. J. 



Cole and C. L. Davis. 



