The Best Papaws 



33 



quite hard when received at this office 

 were placed in a refrigerator and after 

 two weeks were found to be in a perfect 

 condition for eating. It is probable 

 that varieties differ in the evenness of 

 their maturity; but assuming that the 

 variety be a good one, it seems likely 

 that it should be picked before fiilly 

 ripe and allowed to mature indoors. 

 Experiment would easily determine the 

 proper conditions. Several persons who 

 previously despised the papaw were 

 quite converted when given fruits that 

 were not overripe. If this idea of 

 maturity of the fruit is sound, it offers 

 considerable advantages commercially, 

 since the fruit can be picked and 

 shipped while still firm, and allowed to 

 ripen after its arrival at market. 



While hybridization offers some inter- 

 esting possibilities in improving the 

 papaw and reducing the number or size 

 of seeds, it seems likely that simple 

 selection will give quicker good results. 

 If seedlings or inferior trees are grafted 

 to such superior varieties as are de- 

 scribed at the beginning of this article, 

 the esteem of and demand for the fruit 

 should increase rapidly. 



Seeds should be planted while fresh, 



and are excessively slow in growing, 

 sometimes not appearing until a year 

 from the following spring. If given 

 good care they then make fairly rapid 

 growth, and may be transplanted when 

 12 to 18 inches high. This is pref- 

 erably done when they are dormant, 

 but has been done successfully when 

 they are in full leaf; the secret is to 

 take up a very large ball of earth 

 around the roots. They should be 

 grafted early in the spring. It is com- 

 monly supposed that they thrive best 

 with some shade but a number of ex- 

 periments show that they do well in 

 full sunlight. The soil should be well 

 drained, and can hardly be too rich. 

 The tree is notably free from diseases 

 and pests, and is desirable for orna- 

 mental as well as commercial planting. 

 Its large, dark, handsome leaves make it 

 a striking landscape tree for lawns of 

 considerable size. Planted anywhere 

 within the range shown on the attached 

 map, it should succeed; and if it is 

 grafted to a good variety, given suffici- 

 ent fertilizer, not allowed to bear too 

 many fruits in a single cluster, and 

 these fruits properly matured, it can 

 hardly fail to please. 



A New Text-Book of Genetics 



GENETICS AND EUGENICS, a text-book 

 for students of biology and a reference book 

 for animal and plant breeders, by W. E. Castle, 

 Professor of Zoology in Har\'ard University 

 and Research Associate of the Carnegie Insti- 

 tution of Washington. Pp. 353. Illustra- 

 tions 135. Price, $2.00 net. Cambridge, 

 Mass., Harvard University Press, 1916. 



Dr. Castle's book is notable not only 

 because of its contents, but because it is 

 the first comprehensive advanced text- 

 book of genetics in the English language. 

 It contains a general discussion of evo- 

 lution and the historical explanations 

 of it, devotes a short and somewhat 

 inadequate chapter to biometry, and 

 then discusses Mendelism at length, 

 principally from the animal breeder's 

 viewpoint. Dr. Castle's treatment of 



all disputed subjects is frankly critical, 

 a fact which adds much to the value of 

 the work; it is also practical, lists being 

 given of the unit characters so far iso- 

 lated in domestic animals. The treat- 

 ment of eugenics occupies forty-four 

 pages, is conservative throughout, but 

 particularly sound in its treatment of 

 Mendelism in man. A good bibliog- 

 raphy is added, and a reprint of the 

 R. H. S. translation of Mendel's 

 original paper; according to those who 

 have compared this translation with 

 the original, it needs revision. But on 

 the whole the book is admirable both 

 in plan and execution and will be indis- 

 pensable to every serious student of 

 genetics. 



