PRESTPENTIAL ADDRESS. 585 



their influence is a knowledge of their life-history and mode of attack. For the 

 proper estimation and interpretation of the facts in the life-history of one organism 

 it is, of course, necessary to be acquainted with its course in allied forms, and in 

 other divisions of the class to which it belongs. 



Whether we approach the matter from the philosophical or utilitarian side an 

 essential step is to obtain as completely as possible the life-histories of species 

 belonging to the main groups of Protozoa, worked out in detail. Certain aspects ot 

 the Protozoa, such as the shells of the P'oraminifera, have received a great deal of 

 attention, and we have much accumulated knowledge on particular phases of the 

 life-histories of many forms, but of how few groups can it be said that we know 

 the life-history of any one species completely ! For the last thirty years students 

 of biology have begun their studies with an examination of Amceba, yet the life- 

 history of the common forms of amoeba, occurring in streams and ditches, still 

 remains, notwithstanding shrewd surmises as to its course — I think Professor 

 Calkins will permit me to say — unwritten. 



When, therefore, the progi-ess of knowledge of a group reaches a stage in 

 which the main outlines, at least, of the life-history begin to stand forth clearly, 

 it appears to be a matter of importance, not only to the students of that particular 

 group but, as a standard of comparison, to those of allied groups. 



Such a stage has recently been attained in the study of the Foraminifera, and 

 we are now able to sketch with some certainty the general course of the life- 

 history. I have thought, therefore, that the occasion may not be inopportune for 

 me to put the ascertained facts before you, and endeavour to set them in the light 

 of our knowledge of other forms of Protozoa. 



The zoologist who for the last twelve years has been pre-eminent in the inves- 

 tigation of the Protozoa, was Fritz Schaudinn, whose early death occurred 

 last June. Beginning his work in F. E. Schulze's laboratory at Berlin, his 

 earlier investigations were directed to the Foraminifera, to the knowledge of 

 which he made important contributions ; and three years ago he published an 

 account which, as we shall see, completed the main outline of their life-history. 

 His short papers on Actinophrys and various forms of Amceba embody observations 

 of the highest interest. Turning to the investigation of the Sjjorozoa, he was 

 soon led to devote his attention more especially to the organisms which produce 

 disease, and his latest achievement was to demonstrate the cause of one of the 

 greatest scourges of humanity. 



Much of his work rests on preliminary accounts of investigations which his 

 splendid activity in research left him no time to publish indetail— though we may 

 hope that, in some cases at least, it may be found possible for the fuller accounts 

 to appear. The papers which he did complete, such as those dealing with the 

 Alternation of Generations in Coccidia ' and in TrichosphcBrium,'^ are not only contri- 

 butions of first-class merit, but models of research and exposition. In all his worlv 

 he maintained the broad zoological point of view, and his results on the Amaba 

 associated with dysentery are elucidated by those obtained in the study of the 

 Foraminifera. In his insight into the essentials of the problem before him, and his 

 fertility in technical resources, he was, I venture to think, without a rival. 



Having chosen so special a subject, I will endeavour first to set forth briefly the 

 elementary facts of the structure of the Foraminifera, in order that those of my 

 audience who are unfamiliar with them may be able to follow. 



In the hollows between the ridges on a ripple-marked stretch of sand it may 

 often be noticed that the surface is whiter than elsewhere. On scooping up some 

 of the sand and examining it with a lens it will be found that the whiteness is due 

 in part, no doubt, to fragments of shells of molluscs of one kind or another, but in 

 part to the presence of complete shells of minute size and the most exquisite shapes. 

 Microscopically examined it will be found that in nearly all cases the shells are 



' Unt. iib. Generationstvechsel hei Coccidien. Zool. Jahrbiicher. Anat. Bd. 13. 

 1900. 



'^ Unt. ill. Generationswechsel von TricJwsj)lieBrinm, Abh. Akad, Berlin. 1899. 

 Anhang. 



