¿Cómo puedo recorrer un Pandas DataFrame y llamar a una función en cada celda?

Estoy usando el siguiente código para calificar el texto

import textstat
import pandas as pd

test_data = ("""Jonathan pushed back the big iron pot and stood up.
There were no bears. But up the path came his father, carrying his gun. And with
him were Jonathan's Uncle James and his Uncle Samuel, his Uncle John and his
Uncle Peter. Jonathan had never in all his life been so glad to see the uncles.
"Jonathan!'" said his father, "what a fright you have given us! Where have you
been all this time?" """)

textstat.flesch_reading_ease(test_data)

Da un puntaje de 100.48 (muy fácil de leer)

Tengo un csv con columnas 'Título' y 'Texto'. Quiero recorrer cada fila y usar la función textstat.flesch_reading_ease en cada celda de la columna 'Texto'.

Sin embargo, parece que no puedo entenderlo bien.

import textstat 
import pandas as pd
csv = pd.read_csv('my_list_of_texts.csv')


for i, j in csv.iterrows():
     a = textstat.flesch_reading_ease(j)
     print(a)

Esto me da el error TypeError: los objetos 'Series' son mutables, por lo tanto no pueden ser hash