DEPARTMENT OF MARINE BIOEOGY. 133 



the intensity on one side they turn directly from this side. Consequently if 

 the orienting stimulus is the result of a change of intensity, the animals turn 

 toward the side stimulated when it is due to decrease of intensity, and from 

 this side when it is due to increase of intensity. And if this be true, they 

 must be able to distinguish between the stimulations due to the two different 

 conditions of illumination. 



Report upon the Lymphatic System of the Turtle, by Frank A. Stromsten, 



Iozua University. 



During four weeks' stay at the laboratory material for the study of the 

 anatomy and development of the lymphatic system of the loggerhead turtle 

 was collected. About 150 embryos were collected and preserved, and one 

 adult specimen was dissected. 



The loggerhead turtle, which at one time was very abundant in the region 

 of the Dry Tortugas, is now becoming rare. During the present season 

 scarcely a score of the females visited the islands to lay their eggs, while 

 many years ago it is said that as many would crawl upon the beach in a single 

 night. At present every nest is robbed of its eggs and nearly every turtle 

 that reaches the shore is captured and killed by "turtlers" and fishermen. 

 The only eggs allowed to develop during the present season in this entire 

 group of islands, as far as is known to the writer, were those obtained and 

 protected by the laboratory. Unless some means is soon taken for their pro- 

 tection, it can be a matter of but a few years until the loggerhead turtle will 

 practically be extinct in the Florida region. 



The female turtle usually lays her eggs about midnight, some time between 

 10 and 2 o'clock. She crawls up the low sandy beach to a desirable spot 

 above the line of high tide and scoops out a hole about 18 inches deep in the 

 loose sand with her hind flippers. In this nest she deposits from 100 to 150 

 or more eggs. The eggs are spherical in shape and have a diameter of 40 to 

 45 mm. The tough membranous shell is pinkish-white at first, but as devel- 

 opment proceeds it becomes a dead white. The eggs are arranged in a half 

 dozen or more horizontal layers in the nest, and are carefully covered with 

 sand in such a manner as to effectually conceal the exact locality of the nest. 

 The time occupied in laying the eggs is about 30 minutes. During this time 

 it is very easy to capture the turtle, as she is not easily frightened and may be 

 readily approached and turned. She may be left thus lying on her back in- 

 definitely, as she is not able to right herself. 



The eggs intended for study were usually removed from the original nest 

 as needed. In certain cases, however, where the nest was too remote or inac- 

 cessible, it was carefully moved to the neighborhood of the laboratory. In 

 removing the eggs it is very essential that they are not turned or shaken, else 

 the process of development will stop and the embryo die. For that reason 

 the top of each egg was marked with a soft lead pencil before it had been 

 disturbed from its original position in the nest. After being thus marked the 

 eggs are carefully removed, one by one, without turning or jarring, and re- 

 placed in the new nest in as nearly the original condition as possible. 



The embryonic material was fixed in most cases in either "chrom-aceto- 

 formaldehyde" or in Bouin's fluid. A complete series of stages from 12 to 30 

 days of development was obtained. In one complete series the blood-vessels 

 were injected with India-ink. In some of the specimens the lymphatics were 

 also injected. A further consideration of the methods will be given at an- 

 other time. 



The work thus far carried on seems to indicate that the formation of 

 mesenchymal spaces and their subsequent fusion into larger channels play a 



