480 Mr. Edward Heron-Allen [May 21, 



the calcareous cement of wLich it is formed, Cydammina cancellata. 

 The skiagraph (SI. 67) not only reveals its intricate labyrinthic 

 interior, but here, as in the other species, reveals the fact that the 

 individual is of the megalospheric stage of the life-cycle. The 

 method is invaluable for the determination of doubtful species. 

 The two species (SI. (58), Jacnlelhi ohtusa and BoieUma Jabyrwthica, 

 are externally very difficult to distinguisli, but the skiagraph (SI. 60) 

 reveals the simple tubular cavity of the former as contrasted with 

 the labyrinthic interior of the latter, and so determines the identity 

 of the organisms. 



You may rightly ask yourselves in what, beyond the beauty of the 

 shells, consists the interest and value of the elaborate and concen- 

 trated study to which the Foraminifera have been subjected. Their 

 value is both scientific and economic. They are the largest of the 

 unicellular organisms — which are the closest to the beginnings of life 

 — and if ever the structure and nature of protoplasm is to be deter- 

 mined, it is, in my opinion, by the study of the Foraminifera that 

 this conclusion will be arrived at. Economically they form the food 

 of worms, stai fishes, and many of the lower invertebrata, which in 

 turn feed the food-fishes of the world. 



I come now to the concluding and most important section of my 

 discouise, which concerns itself with the phenomena of purpose and 

 intelligence which I have claimed to be exhibited by some of the 

 Foraminifera in the construction of their shells, a claim which has 

 been, and is, denied by several very distinguished zoologists, and 

 admitted, with some reservations, by others no less distinguished.^ 

 There are limits to what is known, but I refuse to admit that tlicre 

 are limits to what is knowable. As Prof. MacBride has jugtly 

 observed : " To put forward an unknown entity as the cause of 

 phenomena which we cannot unravel is not to explain, but in reality 

 to give up the attempt at explanation."- 



The method in which the arenaceous Foraminifera collect and 

 adjust the materials from which they build their marvellous shells is 

 obscure, and though a light begins to dawn upon the process it would 

 take too long to go into the matter on this occasion. Surface tension 

 no doubt plays an important part in the operation, but surface tension 

 will not account for the mysterious fact that certain species such as, 

 to take a single instance (SI. 70) especially, Haplophragmium agglu- 

 tincms, incorporate into their shells fragments of heavy gem minerals 

 such as magnetite, garnet, and topaz, which are not by reason of their 

 specific gravity to be found in the same sand-strata as the relatively 

 light quartz-grains which are mainly used in the construction of the 



^ E. Heron-Allen, On Purpose and Intelligence in the Foraminifera, Proc, 

 Zool. Soc, p. 10G9. London, 1914. 



' E. W. MacBride, in Nature, vol. 94, p. 304. Nov. 19, 1914. 



