Fat-Soluble Vitamines in Marine Animals and Plants. 445 



from fig. 3. They demonstrate a marked increase in growth of the rats from 

 the moment when the oil was given. 



Samples of Diatoms were collected for me by my friend, Prof. H. H. Gran, 

 and Mr. E. Lea on board a Norwegian research vessel. The samples con- 

 sisted of a pure " Diatom-plankton," as this may be found in the sea in the 

 spring before the animals have started their development. The rats fed on 

 these diatoms showed first a sharp increase of growth, and then, after a short 

 time, a marked decline. The idea suggested itself that the diatoms, which 

 contain so much silica, may be very unsuitable as food for a mammal, 

 and diarrhoea was also observed in one case (see fig. 4). In some cases, 

 two drops a day of green oil, extracted by benzene from the dried mass of 

 diatoms, gave at once a marked increase, even in the case of animals which 

 had first been fed on the dried material (fig. 5). Although these experiments, 

 which were hampered by rather scanty material, do not give such a marked 

 and striking growth as the curves of the seaweed, I have no doubt that an 

 increased growth has been demonstrated as a result of addition to the basal 

 diet of the rats of oils extracted from diatoms. 



i GO 

 90 

 80 

 70 



60 

 50 



5 10 15 20 25 30 35 40 

 Fig. 5. — Point 1, ca. - 8 grm. dried diatoms 

 per day. Point 2, 2 drops extract per 

 day. 

























































V 





2 























5 10 15 20 25 30 35 



Fig. 6. — Fresh shrimps ad lib. 



Shrimps and Prawns. 



Fresh shrimps (Crangon) and fresh prawns (Pandalus borealis) were minced 

 and given fresh as an addition to the basal diet of several rats. Figs. 6 and 7 

 show a marked increase in the weight of the rats shortly after the addition of 

 these substances to their diet. 



Dried powder was extracted by benzene, the extracted oil (two drops a day) 

 had in several cases no effect, a fact which I am not able to explain and which 

 must be left for future investigation. 



