238 BULLETIN OF THE BUREAU OF FISHERIES. 
six or eight weeks which constitute an average season. This is a conservative 
estimate based on the following deductions: If all the 24 cars were filled three 
times, allowing two weeks for passing through the moults, with an average 
output per car of 10,000 each time (which is considerably below frequent actual 
production), the total output would be 720,000. With a constant supply of 
fry sufficient to fill the plant to its full capacity throughout the season, this 
estimate could probably be raised. 
As has been stated before, many features of the present installation are 
to be considered as vestigial structures and others as designed for one function 
and adapted to another in the course of the evolution of the plant. A new plant, 
therefore, built to operate the same rearing cars would be different in many 
details. The cost of a plant capable of duplicating the work of the one at 
Wickford has been calculated by Mr. E. W. Barnes, superintendent of the Wick- 
ford plant, at approximately $2,000, specified as follows: 
Cost oF A REARING PLANT CONSISTING OF 24 REARING BOXES CAPABLE OF TURNING OUT OVER 500,000 
LOBSTERLINGS IN A SEASON. 
21% horsepower engine__________------- $200 toa boxes= 9-2 220 ees nS $350 
Househoatwto- 01. s SoS ck es eee 300 | Miscellaneous supplies.___.__..____-_-- 200 
Rourmafts® 22203623 ee eso eee 350 
Gearing OL TRAE ee PO oy SESE LM. ces 400 Total -------------------------- 1, 800 
The above items have been figured economically but quite liberally, and in localities where materials 
can be readily secured the cost might be considerably lessened. The actual cost of rearing lobsters 
to the fourth stage is a little less than $3 per 1,000. This includes labor, food, gasoline, and in fact 
all necessary running expenses, but does not include the cost of egg lobsters. 
This amount would, of course, vary with the time and place where the 
plant was constructed and also with the kind of materials used. 
Self-protective ability of fouwrth-stage lobsters —An acquaintance with thou- 
sands of fourth-stage lobsters from personal observation and through the spe- 
cial scientific studies of members of our staff increases even our former estimate 
of their superiority over the larval lobsters. Immediately after arriving at this 
stage they are able to crawl over the bottom, to burrow and hide, to fight, and 
to forage in most striking contrast to the larval lobsters in any stage of devel- 
opment. In the first few days of the fourth stage the lobsterlings are good 
swimmers—this is their “‘redeeming vice”—but the swimming is strong and 
bears no comparison to the aimless drifting movement characteristic of larval 
stages. The lobsterlings dart hither and thither in pursuit of food, and for the 
first time they show a decided fear and strive to avoid capture. When left in 
the rearing cars, which have a strong internal current of water, thousands of 
these lobsters are often seen all swimming mightily in one direction against the 
strong current for hours at a time; but these same lobsters when taken out of 
the car and put into another one provided with sand and gravel will often take 
immediately to the bottom and behave as if they had always lived in this habitat. 
