Hier wie dort müssen typische Abänderungen auftreten, wenn die Lebensbedingungen für eine Art geändert werden und diese die Fähigkeit besitzt, sich den neuen Verhältnissen anzupassen.
Here, as there, typical modifications must appear once the conditions of life are changed for a species and this species possesses the capacity to adapt to the new circumstances.
typical modifications = typische Abänderungen Bateson has “changes of type”, Sherwood “changes in the type”. As is evident from Mendel’s use of the adjektiv typisch elsewhere (cf. p. 7, s. 9), this refers to the regular behaviour of modified traits in transmission. Mendel is following Carl Friedrich Gärtner here in his use of the word; see the quotation from Gärtner’s book on plant hybridisation on p. 43, s. 9.
once = wenn The German conjunction wenn is ambiguous since it can be understood both in a temporal (as in “when”, which is Sherwood’s choice) and a conditional sense (as in “if”, which is Bateson’s choice). It may be that Mendel was intentionally vague here. Mentioning the “capacity to adapt to new circumstances”, this is certainly the one sentence in the paper that most clearly shows an influence from Charles Darwin, whose Origin of Species Mendel had read and annotated in Heinrich Georg Bronn’s translation. A sentence mentioning persistent modifications under new circumstances at the beginning of the first chapter of Darwin’s Origin was marked by Mendel (see Über die Entstehung der Arten im Thier- und Pflanzen-Reich durch natürliche Züchtung, oder, Erhaltung der vervollkommneten Rassen im Kampfe um’s Daseyn, 2nd ed., transl. by H. G. Bronn, Stuttgart: Schweizerbart, 1863, Mendel Museum, Collection of the Augustinian Abbey, p. 17). But the causalities remain crucially unclear. Neither is it clear whether changed conditions of life directly cause “typical modifications”, nor does Mendel specify the mechanism which is responsible for the “capacity to adapt”.