SCIENCE-GOSSIP. 



237 



a variety of works. So there is a unity of instinct 

 and a variety of adaptations, or a unity of cause 

 and a variety of effects. 



To the instinctive acts of animals we may add 

 those of intelligence, habit and aptitude ; and we 

 must clearly discern between them to avoid 

 confusion. These faculties differ in their nature 

 and origin. We must distinguish between that 

 which is acquired, as habit, from that which is 

 , innate, as instinct ; that which is perfect and 

 'immutable, as instinct, from that which is sus- 

 ceptible of development and improvement, as 

 aptitude ; finally that which is free and deliberate, 

 as intelligence, from that which is purely mechan- 

 ical, as instinct. 



Instinct is never in unison with the rank the 

 animal holds in the animal hierarchy. The most 

 highly developed instincts are not found among 

 the higher but among the lower animals. Insects, 

 in many cases, have a higher instinctive capacity 

 than the huge mammal. The bee, for instance, is 

 more industrious and intelligent than the sheep or 

 the ox. We cannot explain this anomaly ; nor 

 can we tell why, with similar bodies and only 

 minute differences of internal organization, insects 

 differ so widely among themselves. Bees and ants 



furnish an almost endless variety of phenomena ; 

 the ingenuity of these insects excels that of all other 

 animals. We are further embarrassed when we 

 seek the cause that operates in the same instinctive 

 manifestations — the instinct of construction, 

 for example — among animals possessing that cap- 

 acity, as beavers, birds and spiders, or the various 

 manifestations the same animal presents, as the 

 constructive, maternal and social instincts of the 

 bee and ant. However mysterious these phe- 

 nomena, none dare say how far the intellect of 

 man will yet unveil their secrets. Our hopes are 

 sanguine that they will disappear like the mists 

 before the morning sun. 



I intend to employ the term manifestation in 

 preference to that of instinct, the better to dis- 

 tinguish the cause from the effect. The effect 

 I shall term a manifestation. When an animal 

 builds its nest, its cell, or its shell, and when 

 another makes traps to sieze its prey, what chiefly 

 concerns our purpose is the modes of action, the 

 appropriation of organs, and the means employed 

 to attain an end. We must, however, not antici- 

 pate. We hope to study each instinct separately, 

 and for next that of construction. 

 {To be continued.) 



FLOTATION AND ROLLING OF FORAMINIFERA. 



By Arthur Earland, M, 



\ ~\ 7TTH regard to the article in the November 

 number of Science-Gossip, on the " Flota- 

 tion and Rolling of Foraminifera," as a micro- 

 scopist with several years' experience of these 

 organisms, perhaps I may be permitted to give my 

 experience upon the subject. The " nostrum," 

 which Dr. Bryan quotes at the beginning of his 

 article, is by no means an exploded one, but a 

 method which is used by nearly all rhizopodists as 

 a ready means of eliminating the bulk of a gather- 

 ing, and incidentally of separating the more 

 fragile and delicate species from their stouter 

 congeners. Personally I can hardly understand 

 how Dr. Bryan can have been so unfortunate in 

 his results as to have been unable to obtain more 

 than a few pinches of " floatings " from his 

 material. In washing large quantities of my own 

 gatherings, I have frequently separated several 

 ounces of floatings at a time. As evidence of their 

 purity and freedom from foreign matter, with such 

 exceptions as I shall presently notice, I beg to 

 enclose a few sample tubes for your inspection 

 and acceptance. 



I think Dr. Bryan lays far too much stress upon 

 the action of capillarity, or the tension exercised 

 by the surface-film of water. This undoubtedly 

 exists, but I have seldom found it of much import- 



Quekett Micros. Club. 



ance ; and, except in the case of the finest grade of 

 material, it can nearly always be overcome by 

 shaking the vessel containing the water. The same 

 capillarity which acts upon the smooth sand-grains 

 must operate to an even greater extent upon the 

 Foraminifera, many of which are covered with spines 

 and ridges that must necessarily offer an increased 

 resistance to the water. As soon, however, as the 

 surface tension is overcome by the shaking of the 

 vessel and the consequent moistening of the entire 

 surface of the floating particles, the sand-grains 

 sink from their superior gravity, while the Fora- 

 minifera, buoyed up by the air contained in them, 

 continue to float, or remain suspended in the water, 

 from which they may be separated by pouring it 

 off through a strainer. 



The floatings must not, however, be expected 

 to contain all the species to be found in a gathering, 

 for the larger and stouter Foraminifera are too 

 heavy to float, even with the assistance of the 

 air contained in the chambers. A few species, 

 notably some of the Discorbinae and Truncatulinae, 

 do not float for any length of time, owing to the 

 large size of their foramina, which furnish the 

 water with a ready means of access to the interior 

 chambers. On the other hand, there are some 

 Foraminifera which are practically unsinkable, 



