1891.] MICROSCOPICAL JOURNAL. Ill 



brates, proposed to supplement Darwin's hypotheses of the "survival 

 of the fittest " by accounting for the " origin of the fittest." He revived 

 the Lamarkian view that the acquired characters are transmissible, and 

 considers it the chief factor in organic evolution. An extension of 

 Darwin's view was seen to be necessary b}- its astute author, and he re- 

 peatedly stated, in language now seized upon by Cope and his com- 

 peers, that he only called the variations naturally selected on the terms 

 of his theory " chance variations," because he did not know how 

 they were produced, and that acquired characters might to some slight 

 extent be transmissible. Darwin's view presents an immense advantage 

 over its former rival, the view of the elder Agassiz, in the way it har- 

 monizes a vast body of biological data in all departments, no rational 

 interpretation of which has, so far as I know, ever been attempted upon 

 the other view. 



The hypothesis of evolution can hardly be said to have gotten upon 

 any very solid advance ground since Darwin left it. It is now much 

 better understood and in its main features accepted by nearl}' all biolo- 

 gists. But two violently hostile schools have grown out of the effort to 

 deal \vith the cause of diversit}' among living things. One school, the 

 Darwinian, numbers Lankester and Weismann among its leaders and 

 insists that no " acquired characters" are proven to be transmitted ; and 

 so far as facts have been positively gathered it must be confessed that 

 they are in their favor. The " Neo-Lamarkians " do not, however, 

 give up the fight, and in spite of their inability to produce any actual, 

 indisputable cases of the transmission of acquired characters, they col- 

 lect the evidence from lives of creatures apparently evolved and find no 

 adequate explanation of the progression of structure the}^ exhibit, except 

 on the assumption that function so reacts on the organism, though in an 

 unexplained way, as to add to the sum of tendencies to be transmitted 

 the tendency to inherit the acquired structure. The question thus becomes 

 really an inquiry into the nature of heredity. My statement of the case 

 at the beginning of this article is intentionally vague, for it leaves unde- 

 fined the term " parental image." The progress of the article I think 

 shows that we cannot yet say what this transmissible image is. How 

 far is it the race type, how far the individual image .-^ Is it the image of 

 the ever-changing parent at the instance of the egg's first start on its 

 course to independence or at some previous time.^ Is it a partial pro- 

 duct of the diverse tendencies of both parents? Not one of these ques- 

 tions can be answered. While thus the general proposition of evolution 

 as the result of survival of the fittest is virtually settled the further ques- 

 tion of the origin of the fittest still awaits solution. 



Hamline University, AJ>ril 'zs, iSgi. 



Causation of Influenza. — The germs of influenza are generally, at 

 all times, present, and the germs of pneumonia, tuberculosis, and of 

 the other specific diseases are somewhat widely disseminated ; but there 

 must be certain coincident meteorological conditions to irritate the throat 

 and air-passages sufficiently to let the germs gain an entrance to the 

 body. These meteoi'ological conditions are at times the excessive preva- 

 lence of north and northeast winds, and the excessive amount of ozone 

 durinsf certain months. 



