112 REPORTS OF INVESTIGATIONS AND PROJECTS. 



is stronger than from any other natural source. When attempts are made to 

 hinder the course of the animal to the ocean, it immediately falls back on 

 these two tendencies to guide it till the ocean is again in sight. 



(2) Hearing the surf or smelling the water certainly do not enter into 

 consideration. This is borne out by the fact that where direct rays of the 

 sun were eliminated the turtles moved in all directions with equal readiness, 

 though they were but 20 feet from the water, at which distance both the 

 sound and the smell of the water must have been evident. 



(3) Their tendency to move in the direction of the greatest illumination 

 disappears in less than 12 hours after hatching. 



(4) After entering the water these turtles have a definite period of "getting 

 out to sea," followed by a definite period of rest, the process of getting out 

 to sea being governed, as far as direction is concerned, by the source of the 

 strongest illumination. 



(5) The edibility or non-edibility of a substance must be determined for 

 every new object encountered. 



Prof. H. E. Jordan, of the University of Virginia, carried out cytological 

 studies upon echinoderm eggs, these being a continuation of his previous 

 work at Woods Hole upon the eggs of the common starfish. While at Tor- 

 tugas he devoted special attention to a study of the eggs of the large sea- 

 urchin Hipponoe esculenta. His preliminary report is as follows : 



Preliminary Report on a Comparative Cytological Study of Echinoderm 

 Eggs, by H. B. Jordan, University of Virginia. 



My chief object in spending a month at the laboratory at Dry Tortugas 

 was to collect material for a comparative cytological study of the maturation 

 phenomena in various echinoderm eggs. Primarily I desired to determine 

 the relation between chromosomes and nucleolus in the maturing oocyte. It 

 has been claimed for several echinoderm forms that the chromosomes at 

 maturation arise from the nucleolus. I have shown that in Asterias forbesii 

 the chromosomes originate from the nuclear reticulum at the beginning of 

 the growth period of the primary oocyte, persist as a mass of minute bilobed 

 bodies, sometimes in close proximity or even superficially attached to the 

 nucleolus, and at maturation are drawn into the first polar spindle, while the 

 nucleolus fragments and contributes chromatin to the chromosomes, by 

 virtue of which they grow slightly in size. The residue of the nucleolar 

 fragments are resorbed by the cytoplasm. The main problem of this investi- 

 gation is to discover the source and manner of origin of the chromosomes in 

 the oocytes of available echinoderms, and to see whether the normal method 

 actually differs in essentials among different forms or only in minor details. 

 I have thus far been able to extend my research only to include Hipponoe 

 esculenta, a large, white-spined sea-urchin, very abundant in the shallow 

 waters of the reefs in the vicinity of Dry Tortugas. I have on hand material 

 also of two ophiurans, Ophiocoma riisei and O. pimiila, which began to 

 ripen just as I was leaving the Keys, the middle of June, and to which study 

 will shortly be devoted. 



Besides the forms already mentioned, I collected ovarian material also 

 from Diadema setosum, Linchia guildingii, Clypeaster subdepressus, Cidaris 



