GENERAL CONSIDERATIONS 35 



if the results are somewhat less favorable, medium-sized or small follicles 

 develop, and a still less favorable reaction is indicated if merely primordial 

 follicles survive, without undergoing further growth processes; if the reac- 

 tions are more severe, no follicles are seen in the transplant, but there may be 

 only a cyst of the germinal epithelium, ducts, spindle-cell connective tissue 

 and interstitial gland, together with necrotic remnants of the transplanted 

 ovary; under the least favorable conditions, interstitial gland-like tissue may 

 be all that is found, or even this may be missing and necrotic material and 

 fibrous tissue alone may remain. However, it is always necessary to make 

 allowances for the occurrence of accidental injuries to the transplants ; but 

 even if it should be difficult to recognize the latter, errors in the interpretation 

 of the reactions can be avoided by performing a number of experiments, in- 

 stead of relying on a single one. While this method of grading can claim only 

 approximate exactness, still it is very helpful in comparing results obtained if 

 different types of individuality differentials are made to interact. 



In some cases we have used a second type of grades, which were as follows : 

 Grade 6 is given to a typical autotransplant ; grade 5 to a favorable, and grade 

 4 to a less favorable syngenesiotransplant ; grade 3 to a milder and grade 2 to a 

 severe homoiotransplant ; grade 1 has the same meaning in both types of 

 grades. These two systems of grading correspond to each other about as 

 follows : 



Unless specifically so stated, the first type of grading was used. In a general 

 way, these series of reactions correspond to the spectrum of relationships ex- 

 tending from the autogenous through the syngenesious, first to the light and 

 then to the severe homoiogenous reactions. Certain features indicating a still 

 more severe injury are added in the case of heterogenous transplantations. 



As to the terminology employed in distinguishing various types of trans- 

 plantation, very frequently the terms : autoplastic, homoio- or isoplastic, and 

 heteroplastic are used in the literature. However, the affix "plastic" accentu- 

 ates the practical use which is made of transplantation in surgical "plastic" 

 operations. But, transplantations may serve also as a method for the deter- 

 mination of the genetic relationship between the individuality differentials of 

 host and donor, and then it would be more appropriate to designate these 

 various types of transplantation as autogenous, syngenesious, homoiogenous 

 and heterogenous, in order to emphasize the importance of genetic factors in 

 such experiments. 



Transplantations in which the relationships between host and transplant can 



