SYNGENESIOTRANSPLANTATION 75 



intensities of damage in different tissues, and they affect these tissues, there- 

 fore, in a graded manner. In general, only structures with an intermediate 

 degree of sensitiveness are suitable indicators in the analysis of the individual- 

 ity differentials. Tissues, such as cartilage, which are so little sensitive that 

 they react in about the same way after autogenous, syngenesious and homoiog- 

 enous transplantation, are not suitable for this purpose. Likewise, tissues 

 which are so sensitive that they are entirely or largely destroyed by the non- 

 specific injury connected with and following the process of transplantation, 

 such as adult testicle and brain of adult mammals, are not suitable test objects. 

 It is the simple constituents of various organs, those less differentiated as to 

 structure and function, which are usually more resistant and tend to survive 

 even if the conditions following transplantation are injurious. Unfavorable 

 conditions of nourishment, such as deficiency in oxygen, may cause the differ- 

 entiation of tissues — for instance, in the epidermis, in placentoma, in the large 

 follicles of the ovary — and differentiation may result in both increased sensi- 

 tiveness and a diminution or absence of proliferation, or in a proliferation of 

 an abnormal kind, in which mitoses are lacking and, instead, amitotic nuclear 

 multiplications occur; a production of epithelioid and giant cells, and 

 hypertrophy rather than hyperplasia, are then characteristic findings in 

 this condition. The most sensitive structures perish often after homoiotrans- 

 plantation but may remain alive after syngenesiotransplantation. We may now 

 briefly compare the relative sensitiveness of the various organ constituents 

 which we have used for transplantation in the rat and classify them approxi- 

 mately in accordance with the effect which the different types of individuality 

 differentials have on these constituents. 



(1) Skin: In homoiogenous and syngenesious transplantation into the sub- 

 cutaneous tissue the skin, which here forms a cyst, is usually destroyed, not- 

 withstanding the fact that the epidermis as such is resistant. This destruction 

 takes place because in the skin, after transplantation, the injurious action of 

 the connective tissue elements is stimulated and strenghened in a non-specific 

 manner. It is especially the loss of the epithelial lining of the hair follicles 

 which may lead to the stereotropic ingrowth of the connective tissue and the 

 destruction of the cyst, even in autotransplantation. Furthermore, under un- 

 favorable conditions the whole epidermis of the cyst may become keratinized, 

 owing to insufficient nourishment or to mechanical pressure by hyaline con- 

 nective tissue, which may at times fill the cyst. Giant cells form around the 

 hair and the keratin particles. This non-specific action of the connective tissue, 

 and sometimes also of the lymphocytes, in co-operation with the homoio-, 

 or syngenesio-toxins of the host, usually leads to the destruction of the epi- 

 dermis after subcutaneous transplantation, owing to a summation of these 

 partly non-specific and partly specific effects. In some instances, however, the 

 action of the non-specific factors alone may lead to the destruction even of 

 the autogenous skin, although in other cases this may remain alive for a long 

 time or perhaps permanently. Mitoses are usually found in the hair follicles, 

 which are more protected than other structures. 



(2) Ovary: The various constituents of the ovary show a graded power of 



