HERITABLE CHARACTERS OF MAIZE 



XII— MEALY ENDOSPERM' 



P. C, Mangelsdorf 

 Connecticut Agricultural Experiment Station. New Haven Connecticut 



MEALY endosperm is a type of 

 defective seed in which the 

 corneous or "horny" portion 

 of the endosperm is partially or com- 

 pletely lacking. This causes the seeds 

 to be smaller, lighter in color, and 

 soft and mealy in texture. When the 

 corneous endosperm is completely 

 aborted the mature seeds are so soft 

 that they may be easily split apart 

 with the finger nail. The embryo is 

 apparently normal in structure, though 

 somewhat reduced in size. The starch 

 grains when examined under the mi- 

 croscope appear to be normal in size 

 and structure. Because of the greater 

 proportion of starch in the seeds, and 

 the fact that the pericarp attains al- 

 most complete development regardless 

 of the size of the endosperm, the 

 mealy seeds have a characteristic dull 

 and shrivelled appearance not readily 

 confused with the character shrunken 

 endosperm described by Hutchinson." 



Mealy seeds were first observed by 

 Dr. D. F. Jones on a segregating self- 

 pollinated flint ear grown by Dr. E. 

 G. Anderson at Cornell. On account 

 of their resemblance to the partial de- 

 fectives described by the former in 

 the Journal of Heredity,'' Dr. Ander- 

 son very kindly furnished him with 

 seed from this ear. This was grown 

 in the summer of 1920 and crossed 

 v/ith several other types of defectives. 

 The F2 generation, grown in 1921, was 

 turned over to the writer for classi- 

 fication and further investigation, to- 



gether with the data previously ob- 

 tained by Dr. Jones. 



Separating and counting of the 

 kernels from nine selfed ears show 

 this character to be a simple Men- 

 delian recessive. Table I shows the 

 tabulated results from these nine ears. 



Table L 



Ear No. 



Mealy 



277 



277—1 ... 

 277 — 2 . . . 

 277 — I — I 

 277 — I — 2 

 277—1—3 

 277—1—4 



277—1—5 

 277 — I — 6 



Total 



Expected 3:1. 

 Deviation . . . . 



It was impossible to cross this char- 

 acter directly with other defectives on 

 account of the difficulty of obtaining 

 any of these types in a homozygous 

 condition. However, when a number 

 of segregating plants were crossed, all 

 of the Fi seeds were normal. If the 

 two types of defectives are genetically 

 distinct we would expect to get in the 

 second generation four kinds of ears, 

 as follows : 



L Ears not segregating. 



2. Ears segregating partial defec- 

 tives. 



3. Ears segregating mealy defec- 

 tives. 



4. Ears segregating both types. 



^ contribution from Bussey Institution, Harvard University. 



^Hutchison. C. B. Heritable Characters of Maize— Shrunken Endosiperm. Journal of 

 Heredity, xii 76 :83. 



"Jones, D. F. Heritable Characters of Maize— Defective Seeds. Journal of Heredity, 

 xi:i6o-i67. 



359 



