REPOET OF COMMISSIONERS OF INLAND FISHERIES. 77 



ui)wards and interfere with the movements of the propeller, in the 

 manner of transmitting and counting fry, etc., etc. These things, 

 however, are not of general interest, though they are important 

 steps in the progress of the work. 



The growth of parasites on the bodies of the young lobsters con- 

 stitutes one of the most serious difficulties now left for us to contend 

 with. Oftentimes young lobsters are seen to have a fuzzy growth 

 on the body and on the limbs (See Figs. 15, 16 and 17.) Under the 

 microscope this growth is resolved into a tangled mass of diatoms 

 and stalked protozoa, which, though they are probably not true 

 parasites, often so encumber the movements of the lobster and in- 

 terfere with its feeding and moulting as to finally cause its death. 

 The growth is found most often on lobsters in the third stage. 

 There are two possible reasons for this : in the first place, the bags 

 containing the lobsters of this stage have usually been in the water 

 for more than a week, and the microscopic forms collect in great 

 numbers on the walls of the bag (see Fig. 17), so that perhaps the 

 lobsters become infected from contact with them here; in the sec- 

 ond place, the third stage is of longer duration than the two pre- 

 ceding ones, so that the parasites have a longer time in which to 

 settle and grow; for with the shedding of the skin, of course, the 

 parasites are thrown off. Why they are more abundant in the 

 latter part of the season (July) is not easily explained. They are 

 not so serious a menace to the life of the lobster under the present 

 method of operation as they were in the older experiments, when 

 the lobsters were not stirred. In the season preceding the install- 

 ment of the present apparatus, some of the specimens were so 

 thickly overgrown that they showed no resemblance to a lobster or 

 any other living creature. We may perhaps also congratulate our- 

 selves that this pest is not so abundant at our station as it ii in 

 other localities, for example, at Woods Holl. 



How to combat or avoid this evil is a problem yet to be solved. 

 Extermination is, of course, out of the question. Experiments in 

 shading the bags were tried at W^jods Holl. A screen was put up to 



