TRANSACTIONS OK SECTION D. 669 



function as if tliey belonged to different genera, or even to different families. 

 Zoologists have made the wildest mistakes in classifying larvre whose subsequent 

 history was at the time unknown. The naturalist who devotes himself to life- 

 histories shares the advantage of the naturalist who explores a new continent. A 

 wealth of new forms is opened out before him. Though Swammerdam, Reaumur, 

 De Geer, Vaughan Thompson, Johannes Miiller and a crowd of less famous 

 naturalists have gone before us, so much remains to be done that no zealous 

 inquirer can fail to discover plenty of untouched subjects in any wood, thicket, 

 brook or sea. 



Whoever may attempt this kind of work will find many difficulties and many 

 aids. He will of course find abundant exercise for all the anatomy and physiology 

 that he can command. He will need the systems of descriptive Zoology, and will 

 often be glad of the help of professed systematists. The work cannot be well 

 done until it is exactly known what animal is being studied. For want of this 

 knowledge, hardly attainable 150 years ago, Edaumur sometimes tells us curious 

 things which we can neither verify nor 'correct ; at times we really do not know 

 what animal he had before him. The student of life-histories will find a use for 

 physics and chemistry, if he is so lucky as to remember any. Skill in drawing is 

 valuable, perhaps indispensable. 



If by chance I should be addressing any young naturalist who thinks of attend- 

 in"' to life-histories, I would beg him to study his animals alive and under natural 

 conditions. To pop everything into alcohol and make out the names at home is 

 the method of the collector, but life-histories are not studied in this way. It is 

 often indispensable to isolate an animal, and lor this purpose a very small habita- 

 tion is sometimes to be preferred. The tea-cup aquarium, for instance, is often better 

 than the tank. But we must also watch an animal's behaviour under altogether 

 natural circumstances, and this is one among many reasons for choosing our subject 

 from the animals which are locally common. Let us be slow to enter into con- 

 troversies. After they have been hotly pursued for some time, it generally turns 

 out that the disputants have been using words in different senses. Discussion is 

 excellent, controversy usually barren. Yet not always ; the Darwinian controversy 

 was heated, and nevertheless eminently productive ; all turns upon the temper of 

 the men concerned, and the solidity of the question at issue. One more hint to 

 young students. Perhaps no one ever carried through a serious bit of work without 

 in some stage or other longing to drop it. There comes a time when the first 

 impulse is spent, and difficulties appear which escaped notice at first. Then most 

 men lose hope. That is the time to show that we are a little better than most 

 men. I remember as a young man drawing much comfort from the advice of a 

 colleague, now an eminent chemist, to whom I had explained my difficulties and 

 fears. All that he said was : ' Keep at it,' and I found that nothing more was 

 wanted. 



I greatly believe in the value of association. It is good that two men should 

 look at every doubtful structure and criticise every interpretation. It is often 

 good that two talents should enter into partnership, such as a talent for description 

 and a talent for drawing. It is often good that an experienced investigator should 

 choose the subject and direct the course of work, and that he should be helped by 

 a junior, who can work, but cannot guide. It seems to me that friendly criticism 

 before publication is often a means of preventing avoidable mistakes. I am sorry 

 that there should be any kind of prejudice against co-operation, or that it should 

 be taken to be a sign of weakness. There are, I believe, very few men who are 

 so strong as not to be the better for help. One difficulty would be removed if 

 known authors were more generous in .acknowledging the help of their assistants. 

 They ought not to be slow to admit a real helper to such honour as there may be 

 in joint-authorship. 



Among the most important helps to the student of life-histories must be 

 mentioned the zoological stations now maintained by most of the great nations. 

 The parent of all these, the great zoological station at Naples, celebrated its 

 twenty-fifth anniversary last April, so that the whole movement belongs to our 

 own generation. How would Spallanzani and Vaughan Thompson and Johannes 



