PROGRESS IN BIOLOGICAL INQUIRIES 



59 



Almost all of the organisms belong to groups typicall}^ found on 

 rocks or other submerged structures near shore, which substantiates 

 a previous conclusion that fouling occurs when ships are in harbor. 

 Light also has been found to be a very important factor in the attach- 

 ment of the larvae of the various forms that have been found on the 

 bottoms of ships. A study of the reactions of the cyprid larvae of 

 Balanus ehurnens and B. ampliitrite has been completed, which shows 

 that spectral colors of equal values have different stimulating effi- 

 ciencies. Light in the field of green and blue-green was found to 

 have the maximum stimulating effect. For both of the barnacles 

 studied the relative values were approximately equal. 



Seasonal periodicity for attaching stages of many of the organ- 

 isms causing fouling has been studied. In this connection 10 sets 

 of panels have been issued to 10 naval vessels, the panels to be 

 submerged in each port of call and then carefully preserved in order 

 to correlate the fouling on the ship's bottom with the place of at- 

 tachment as determined by the ship's log. 



The life histories of the several barnacles found at Beaufort, 

 N. C, are being studied in the hope of throwing light (1) on the 

 problem of selective attachment; (2) on the formation of a work- 

 able key for recognition of various species of barnacles in their 

 larval stages; and (3) to provide data for a critical analysis of some 

 of the divergent results obtained during the extensive series of in- 

 vestigations by the paint division of the Navy Department. 



Considerable time has thus far been spent in tabulating the results 

 of the investigation and in its organization into the form of a 

 report. 



INVESTIGATIONS PERTAINING TO FISH-CULTURAL OPERATIONS 

 PATHOLOGY OF FISHES 



The investigations on Octoimtus salnioriis^ a parasitic flagellate of 

 trout, were continued during the summer and fall by Dr. H. S. 

 Davis, and the results are now being prepared for publication. This 

 parasite, which lives in the intestine of the host, has a very inter- 

 esting life history which shows that there are two distinct cycles 

 in its development. During one stage of its existence the parasite 

 lives within the cells lining the anterior end of the intestine and 

 the pyloric caeca, while during the second or flagellated stage it is 

 found swimming actively about in the fluid contents of the intestine. 



The intracellular stage first appears as an inconspicuous rounded 

 organism much smaller than the epithelial cell in which it occurs. 

 The parasite^ quickly grows to many times its original size and then 

 divides into a number of small cells similar to the original, Avhich 



